970 vs. 970fx

[alexf]

I am thinking of getting a G5 2.0GHz and am debating between a Rev. A and Rev. B (probably with the upgraded graphics card)... I want to pretend for a moment that money isn't a factor (although in reality it is) and compare the two.

Would I notice any difference between the original 970 chip and the 970fx? It the 970fx really superior in many ways? Energy consumption is important to me, and I hear that the chip is improved in this area, but how big a difference would this really be? And how about performance improvement?

Lastly, is the internal architecture any different on the two models? if I recall, the insides look slightly different in some ways, or...?

I'll be grateful for any expert guidance. :)

[invaLPsion]

Would I notice any difference between the original 970 chip and the 970fx? It the 970fx really superior in many ways? Energy consumption is important to me, and I hear that the chip is improved in this area, but how big a difference would this really be? And how about performance improvement?

Lastly, is the internal architecture any different on the two models? if I recall, the insides look slightly different in some ways, or...?

I'll be grateful for any expert guidance. :)

You will not notice a shred of difference between the two chips. The 970FX has double the data cache, however, the difference in performance is absolutely unnoticeable. The chip supposedly runs quieter and with less power consumption, but reports from users indicate that the difference is minimal.

In terms of internal architecture, the new G5s are .25 inches wider.

[Sun Baked]

You will not notice a shred of difference between the two chips. The 970FX has double the data cache, however, the difference in performance is absolutely unnoticeable. The chip supposedly runs quieter and with less power consumption, but reports from users indicate that the difference is minimal.

In terms of internal architecture, the new G5s are .25 inches wider.Actually they are the same the dude that did the article ****ed up.

http://forums.macrumors.com/attachment.php?attachmentid=11081

[alexf]

In terms of internal architecture, the new G5s are .25 inches wider.

What exactly is .25 inches wider?

Also, when you say the chip runs quieter, do you mean less fan noise? I didn't know that chips really made noise to begin with... (perhaps my ignorance)

[invaLPsion]

What exactly is .25 inches wider?

Also, when you say the chip runs quieter, do you mean less fan noise? I didn't know that chips really made noise to begin with... (perhaps my ignorance)

The case is wider by a quarter of an inch.

The fans are what I meant as being quieter.

[alexf]

The case is wider by a quarter of an inch.

The fans are what I meant as being quieter.

So the computer is actually physically larger? This is surprising...

(As if it wasn't already big enough! Then again, .25 inches is almost nothing...)

Are the fans really noticeably quieter? Has anyone done any comparisons?

[shadowband]

I am thinking of getting a G5 2.0GHz and am debating between a Rev. A and Rev. B (probably with the upgraded graphics card)... I want to pretend for a moment that money isn't a factor (although in reality it is) and compare the two.

Would I notice any difference between the original 970 chip and the 970fx?
Don't assume that the rev b 1.8/2.0 powermacs have the 970fx chip. I just took delivery of a BTO 2.0GHz powermac last month and it has the 970. The 970fx will most likely be phased into the 1.8/2.0 line at some point, but there's no confirmation that this has happened as of yet.

To determine which chip is used, refer to the procedure following thread:
http://forums.macrumors.com/showthread.php?t=84191

[QCassidy352]

Actually they are the same the dude that did the article ****ed up.

according to that graphic, the newer chip consumes MUCH less power... am I missing something?

[alexf]

Don't assume that the rev b 1.8/2.0 powermacs have the 970fx chip. I just took delivery of a BTO 2.0GHz powermac last month and it has the 970. The 970fx will most likely be phased into the 1.8/2.0 line at some point, but there's no confirmation that this has happened as of yet.

To determine which chip is used, refer to the procedure following thread:
http://forums.macrumors.com/showthread.php?t=84191

Right, but I recall reading a couple of recent posts that stated that all of them are indeed now shipping with the new chip.

In any case, as the previous poster stated, it probably wouldn't matter at all to me as the end user what chip is inside performance-wise, but as far as noise and energy are concerned, the new chip might be nicer.

[Sun Baked]

according to that graphic, the newer chip consumes MUCH less power... am I missing something?Yes, look at the highlighted text in the quote -- the new 970FX CPUs do not have a larger L1 inst cache, which is what the author of the original article was saying.

[alexf]

according to that graphic, the newer chip consumes MUCH less power... am I missing something?

Yes, actually it's about 50%! If this is true, that is quite a bit. :eek:

[Sun Baked]

So the computer is actually physically larger? This is surprising...

(As if it wasn't already big enough! Then again, .25 inches is almost nothing...)

Are the fans really noticeably quieter? Has anyone done any comparisons?Hmm...

Lowendmac (along with many other sites) has the SP1.6PM as

size (HxWxD): 20.1" x 8.1" x 18.7" (51.1 x 20.6 x 47.5 cm)

And apple has the new DP2.5PM as

# Height: 20.1 inches (51.1 cm)
# Width: 8.1 inches (20.6 cm)
# Depth: 18.7 inches (47.5 cm)

---
I can't seem to find the .25 missing inches. :(

[ifjake]

i was under the impression that less power consumption meant less heat generated, but it seems that that's not correct as that graphic states that the junction temp. range, whatever that means, is larger for the 970fx. anyone know what's up?

[Sun Baked]

i was under the impression that less power consumption meant less heat generated, but it seems that that's not correct as that graphic states that the junction temp. range, whatever that means, is larger for the 970fx. anyone know what's up?Motorola did the same thing for the "performance spec" processors that Apple was consuming.

The physically hotter temp should allow IBM/Apple to turn the clock up a bit.

It wouldn't be too surprising to see the 2.5GHz CPU being classified as a 105°C chip.

---

Of course under Motorola, their market was the 85°C range for the embedded market and the chips Apple used weren't really part of their public spec.

One of the reason the chips on their website always took so long to catch up in speed to the PowerMacs -- because the PowerMacs were able to use a hotter chip and the rest of Motorola's market didn't.

[QCassidy352]

Yes, look at the highlighted text in the quote -- the new 970FX CPUs do not have a larger L1 inst cache, which is what the author of the original article was saying.

yeah, I got that part of it... but some ppl were saying that there was no practical difference between the two chips. Seems to me that 1/2 the power consumption would be a practical difference.

[vga4life]

according to that graphic, the newer chip consumes MUCH less power... am I missing something?

It's not true.

Nobody has yet managed to make a 90 nm chip show any significant power savings compared to 130nm. All the industry estimates of power savings based on the savings seen in previous die shrinks turned out to be wrong.
(Compounding the problem, the 90nm chips are physically smaller. Result: more heat in a smaller area requiring extreme cooling measures.)

Intel's 90nm Prescott P4's actually consume much more power than the previous 130nm Northwood core. IBM made big claims of 90nm power savings before they actually started making 90nm chips. Now you can dig all day but you will never find real power consumption numbers for the 970fx. They're simply unpublished and unavailable unless you sign NDAs (or get ahold of a 970fx and run your own analysis). That graphic is long, long, out of date.

-vga4life

[alexf]

It's not true.

Nobody has yet managed to make a 90 nm chip show any significant power savings compared to 130nm. All the industry estimates of power savings based on the savings seen in previous die shrinks turned out to be wrong.
(Compounding the problem, the 90nm chips are physically smaller. Result: more heat in a smaller area requiring extreme cooling measures.)

Intel's 90nm Prescott P4's actually consume much more power than the previous 130nm Northwood core. IBM made big claims of 90nm power savings before they actually started making 90nm chips. Now you can dig all day but you will never find real power consumption numbers for the 970fx. They're simply unpublished and unavailable unless you sign NDAs (or get ahold of a 970fx and run your own analysis). That graphic is long, long, out of date.

-vga4life

So if this is all true, what is all the hype about the 970fx all about?

I am confused: I thought the 970fx was supposed to run cooler, and therefore could be fit into a smaller computer (like the iMac), as well as run more silently due to less fan noise. What's up?

[vga4life]

So if this is all true, what is all the hype about the 970fx all about?

I am confused: I thought the 970fx was supposed to run cooler, and therefore could be fit into a smaller computer (like the iMac), as well as run more silently due to less fan noise. What's up?

It *WAS* supposed to be cooler, etc. It's not.

The only upside to a 90nm chip right now is for the manufacturer: more chips fit on a single wafer of silicon, increasing fab capacity. For everyone else (computer manufacturers who bhave to design fancy cooling systems for these chips and consumers who have to live with hotter, noisier computers), 90nm chips just plain suck.

In the case of the 970fx, IBM is seeing such poor yields that this capacity increase hasn't materialized - 970fx yields are ultra-low, and this is why the G5 imac is nowhere to be found. Not enough CPUs.

Basically the 970fx is a motorola-grade fiasco.

-vga4life

[alexf]

It *WAS* supposed to be cooler, etc. It's not.

The only upside to a 90nm chip right now is for the manufacturer: more chips fit on a single wafer of silicon, increasing fab capacity. For everyone else (computer manufacturers who bhave to design fancy cooling systems for these chips and consumers who have to live with hotter, noisier computers), 90nm chips just plain suck.

In the case of the 970fx, IBM is seeing such poor yields that this capacity increase hasn't materialized - 970fx yields are ultra-low, and this is why the G5 imac is nowhere to be found. Not enough CPUs.

Basically the 970fx is a motorola-grade fiasco.

-vga4life

If I may ask, where did you get this information?

Also, the new iMacs are due to be released in a matter of days. From my understanding the 970fx was an important part of the reason the G5 iMac is possible.

[vga4life]

If I may ask, where did you get this information?

Also, the new iMacs are due to be released in a matter of days. From my understanding the 970fx was an important part of the reason the G5 iMac is possible.

IBM's 90nm yield problems are well known (especially in the 300mm wafer facility):
http://reviews.infoworld.com/article/04/07/19/HNibmchipgroup_1.html?PROCESSORS

Apple explicitly said in their conference call that chip availability was the reason the imac G5 was delayed until next month.

The 970fx probably does use a little less power than the 970, but not 50% less. Also the heat is concentrated in a smaller area due to the smaller die size, meaning more efficient cooling is necessary (see the 2.5GHz PowerMac's setup)

-vga4life

[alexf]

IBM's 90nm yield problems are well known (especially in the 300mm wafer facility):
http://reviews.infoworld.com/article/04/07/19/HNibmchipgroup_1.html?PROCESSORS

Apple explicitly said in their conference call that chip availability was the reason the imac G5 was delayed until next month.

The 970fx probably does use a little less power than the 970, but not 50% less. Also the heat is concentrated in a smaller area due to the smaller die size, meaning more efficient cooling is necessary (see the 2.5GHz PowerMac's setup)

-vga4life

So essentially, does this mean that, say a G5 with a 970 chip may in fact be QUIETER than a newer one with the 970fx chip?

Right, I understand the chip availability problem for the iMac, but what does this have to do with cooling problems?

[Catfish_Man]

It *WAS* supposed to be cooler, etc. It's not.

The only upside to a 90nm chip right now is for the manufacturer: more chips fit on a single wafer of silicon, increasing fab capacity. For everyone else (computer manufacturers who bhave to design fancy cooling systems for these chips and consumers who have to live with hotter, noisier computers), 90nm chips just plain suck.

In the case of the 970fx, IBM is seeing such poor yields that this capacity increase hasn't materialized - 970fx yields are ultra-low, and this is why the G5 imac is nowhere to be found. Not enough CPUs.

Basically the 970fx is a motorola-grade fiasco.

-vga4life

I'm sorry, but you're wrong. Typical power for a 2GHz 970fx is 24.5 watts (this is probably counting PowerTune, so the peak/typical ratio is going to be somewhat higher than for the 970). For a 2GHz 970 it's 66 watts. This has been confirmed from IBM in more than one place (see the G5 threads on macnn and arstechnica). Either they're blatantly lying, or you're wrong (or, option 3, you have access to non-public info about the fx and are violating your NDA).

[alexf]

I'm sorry, but you're wrong. Typical power for a 2GHz 970fx is 24.5 watts (this is probably counting PowerTune, so the peak/typical ratio is going to be somewhat higher than for the 970). For a 2GHz 970 it's 66 watts. This has been confirmed from IBM in more than one place (see the G5 threads on macnn and arstechnica). Either they're blatantly lying, or you're wrong (or, option 3, you have access to non-public info about the fx and are violating your NDA).

Wow, this is getting interesting...

I (a measely designer who knows virtually nothing about this and just wants to know which chip would be quieter and more power efficient), will sit back and enjoy watching you two duke it out (respectfully, of course). :)

[oingoboingo]

If I may ask, where did you get this information?

Also, the new iMacs are due to be released in a matter of days. From my understanding the 970fx was an important part of the reason the G5 iMac is possible.

The new iMacs are already months late. The PPC 970FX has supposedly been in products since January 2004 (when the XServe G5 was announced and shown at MWSF). The fact that it is now almost September and we are still waiting for the iMac G5, and supplies of high-end PowerMac G5s are still highly limited indicates that the 970FX is not being produced in large numbers yet. Apple said as much in their most recent financial results conference call where they blame IBM for the delay in shipping iMac G5s.

[Sun Baked]

And IBM testing (http://episteme.arstechnica.com/eve/ubb.x?a=tpc&s=50009562&f=8300945231&m=9080959175&r=335009425631#335009425631) of a production PowerMac G5 2.0GHz PPC970 says it got 79W max power dissipation using RC5-72.

While Freescale (http://episteme.arstechnica.com/eve/ubb.x?a=tpc&s=50009562&f=8300945231&m=9080959175&r=643007625631#643007625631) tested the same type of machine using Dhrystone (their benchmark for typical) at 91.1W

So no telling what it really is, but since there is an enire module running it looks like the CPU+daughtercard Powersupply/circuits can be up there quite a bit.

[osprey76]

i was under the impression that less power consumption meant less heat generated, but it seems that that's not correct as that graphic states that the junction temp. range, whatever that means, is larger for the 970fx. anyone know what's up?

You're confusing heat and temperature. The chip does produce less heat, but does apparently run at a higher temperature.

The concept of heat versus temperature confuses a lot of people. A rough parallel would be a gallon of water at 200F versus a cup of water at 212F and cooling each to 100F. Sure the cup of water has a higher temperature, but the gallon of water contains more heat. This is why you read of fusion experiments that reach temperatures of millions of degrees (F or C), but they don't contain enough heat to boil a cup water. There are a few dozen atoms at millions of degrees, and several million water atoms at room temperature. You could toss the fusion core in the water and it would barely sizzle for a microsecond as the fusion atoms are cooled very quickly by the enormous (relatively) amount of water.

The heat a chip produces is directly proportional to the power it uses. So, the 970 will probably produce about twice as much heat as the 970FX. However, the smaller surface area of the 970FX chip means that it is harder to pull the heat out and results in higher temperatures. Surface area tosses in another important aspect of heat transfer and I hope this helps everyone understand better rather than confuse them!

[alexf]

You're confusing heat and temperature. The chip does produce less heat, but does apparently run at a higher temperature.

The concept of heat versus temperature confuses a lot of people. A rough parallel would be a gallon of water at 200F versus a cup of water at 212F and cooling each to 100F. Sure the cup of water has a higher temperature, but the gallon of water contains more heat. This is why you read of fusion experiments that reach temperatures of millions of degrees (F or C), but they don't contain enough heat to boil a cup water. There are a few dozen atoms at millions of degrees, and several million water atoms at room temperature. You could toss the fusion core in the water and it would barely sizzle for a microsecond as the fusion atoms are cooled very quickly by the enormous (relatively) amount of water.

The heat a chip produces is directly proportional to the power it uses. So, the 970 will probably produce about twice as much heat as the 970FX. However, the smaller surface area of the 970FX chip means that it is harder to pull the heat out and results in higher temperatures. Surface area tosses in another important aspect of heat transfer and I hope this helps everyone understand better rather than confuse them!

Thank you, that does clarify things quite a bit.

But the real question: what does this mean in terms of cooling systems? Some have written that the 970fx chip requires more work to be cooled off (probably resulting in a noisier machine), while others have written the exact opposite.

What do you think?

[alexf]

The new iMacs are already months late. The PPC 970FX has supposedly been in products since January 2004 (when the XServe G5 was announced and shown at MWSF). The fact that it is now almost September and we are still waiting for the iMac G5, and supplies of high-end PowerMac G5s are still highly limited indicates that the 970FX is not being produced in large numbers yet. Apple said as much in their most recent financial results conference call where they blame IBM for the delay in shipping iMac G5s.

So, what I still don't understand is that, if the newer 970fx chips do in fact get hotter and require a more elaborate cooling system (if this is true), why don't they just put the older 970 chips into the new iMacs?

Am I missing something?

[Mord]

It *WAS* supposed to be cooler, etc. It's not.

The only upside to a 90nm chip right now is for the manufacturer: more chips fit on a single wafer of silicon, increasing fab capacity. For everyone else (computer manufacturers who bhave to design fancy cooling systems for these chips and consumers who have to live with hotter, noisier computers), 90nm chips just plain suck.

In the case of the 970fx, IBM is seeing such poor yields that this capacity increase hasn't materialized - 970fx yields are ultra-low, and this is why the G5 imac is nowhere to be found. Not enough CPUs.

Basically the 970fx is a motorola-grade fiasco.

-vga4life

dude there was a thing on xlr8yourmac which had the recorded power consumption of the 970fx and it did average at 25w and peak at 35w, and this was a single 2.0GHz xserve.

as for the dude that was confused as to why ibm states that the 970fx is stated as a higher temp cpu as a 970 it means it needs less cooling and will run at 105 degrees stable.

[shadowband]

Thank you, that does clarify things quite a bit.

But the real question: what does this mean in terms of cooling systems? Some have written that the 970fx chip requires more work to be cooled off (probably resulting in a noisier machine), while others have written the exact opposite.

What do you think?
The real answer will require a bake-off between a 2.0GHz powermac using PowerPC G5 version 2.2 CPUs (PPC970) and one using PowerPC G5 version 3.0 CPUs (PPC970fx). The Hardware Monitor (shareware) records the CPU die temperature, CPU voltage, and the speed of the various fans. The fan speed comparison is ultimately what is required to determine whether or not the 970fx results in a quieter system. Anyone want to start a pool ;)

[osprey76]

Thank you, that does clarify things quite a bit.

But the real question: what does this mean in terms of cooling systems? Some have written that the 970fx chip requires more work to be cooled off (probably resulting in a noisier machine), while others have written the exact opposite.

What do you think?

That sounds valid to me. With a higher heat density (lower power, but a much smaller area to extract it) you would need another wind tunnel machine or a new cooling system. A la liquid cooling in the 2.5 machine. Water is a much better cooling medium than air. You use the water to pull the heat out of the processor and then you can use a radiator type device to spread the heat out and use relatively low velocity air to vent the heat out of the case.

Whether this ends up being noisier or not is dependent on several factors. Velocity of the air in the case, fan speed, heat sink, etc. It just all depends on how Apple engineered the cooling solution and if they made any changes from Rev. A to Rev. B on the air-cooled machines.

[alexf]

It just all depends on how Apple engineered the cooling solution and if they made any changes from Rev. A to Rev. B on the air-cooled machines.

Did they make any changes? Someone here must know...

[Flynnstone]

I doesn't make a big difference between the Rev A & B.
The differences from the user point is likely very little.
The rest is ... academic. A roughly 50 watt difference will not make a small rodent's buttocks.
The problem with 90nm chips is the leakage current is excessive.

I think the more important question is if the power supply clicking is gone in the rev Bs.

[alexf]

A roughly 50 watt difference will not make a small rodent's buttocks.

Do small rodents really have buttocks? :)

[oingoboingo]

So, what I still don't understand is that, if the newer 970fx chips do in fact get hotter and require a more elaborate cooling system (if this is true), why don't they just put the older 970 chips into the new iMacs?

Am I missing something?

You've got me there. I don't know. At this stage maybe Apple should just rename the MPC 7447A to 'G5' and make the launch.

[Abstract]

Heh, yeah, or go back to 180 nm chips, hike the 970 nm up to 3GHz, and away we go!

Of course, this depends on whether its true that these new 90nm cpu's produce less heat, but are technically more difficult to cool. But hey, just keep making the die sizes larger and larger, and according to the information posted in this thread so far, we could be at 4GHz by next week!

[alexf]

Perhaps the reason that Apple doesn't put the original 970 chips in the iMac is simply cost - the newer chips are simply cheaper to make.

In any case, I will be very curious to see the cooling system on the new iMacs... If the new chips really do run hotter and need to be cooled off better I am curious as to how Apple will manage this in a small enclosure without turning the machine into another windtunnel.

[alexf]

The real answer will require a bake-off between a 2.0GHz powermac using PowerPC G5 version 2.2 CPUs (PPC970) and one using PowerPC G5 version 3.0 CPUs (PPC970fx). The Hardware Monitor (shareware) records the CPU die temperature, CPU voltage, and the speed of the various fans. The fan speed comparison is ultimately what is required to determine whether or not the 970fx results in a quieter system. Anyone want to start a pool ;)

Yes, this would be a good idea...

Anyone?

BTW, I think I may have read somewhere that there is a slight speed difference between a similar GHz 970 and 970fx.

Can anyone confirm this?

[Sun Baked]

Here's an IBM graphic on the 2.5GHz PPC970fx...

Figure 2. Maximum power envelope from 0.8 to 1.3 V showing the power reduction possible through power-tuning methods.

http://www-1.ibm.com/technology/power/newsletter/august2004/images/article7_2.jpg

Figure 3. Maximum power and nap power envelopes showing transitions from maximum power to nap power at f, f/2 and f/4, and then to deep nap at f/64.

http://www-1.ibm.com/technology/power/newsletter/august2004/images/article7_3.jpg

[alexf]

Here's an IBM graphic on the 2.5GHz PPC970fx...

Figure 2. Maximum power envelope from 0.8 to 1.3 V showing the power reduction possible through power-tuning methods.

http://www-1.ibm.com/technology/power/newsletter/august2004/images/article7_2.jpg

Figure 3. Maximum power and nap power envelopes showing transitions from maximum power to nap power at f, f/2 and f/4, and then to deep nap at f/64.

http://www-1.ibm.com/technology/power/newsletter/august2004/images/article7_3.jpg

:confused: It's all Greek to me...

[Sun Baked]

:confused: It's all Greek to me...IBM is stating that the Maximum Power Number is twice the 50W Typical number for the PPC970FX -- 100W.

Which is much higher than the numbers they gave us for Maximum Power Dissipation for either the 1.8/2.0 PPC970 which had 51W/66W Typical.

---

EDIT -- If you look here (http://forums.macrumors.com/showthread.php?p=1003470#post1003470) you'll see some more evidence of the problems IBM has been having with the PPC970 (aka, low voltage operation & reliability at higher clock speed).

[alexf]

IBM is stating that the Maximum Power Number is twice the 50W Typical number for the PPC970FX -- 100W.

Which is much higher than the numbers they gave us for Maximum Power Dissipation for either the 1.8/2.0 PPC970 which had 51W/66W Typical.

---

EDIT -- If you look here (http://forums.macrumors.com/showthread.php?p=1003470#post1003470) you'll see some more evidence of the problems IBM has been having with the PPC970 (aka, low voltage operation & reliability at higher clock speed).

Right, understood - thanks.

Yet the question stilll remains: would me, as the end user, notice any performance difference at all between the 2 chips? Or is this still unknown?

[Catfish_Man]

IBM is stating that the Maximum Power Number is twice the 50W Typical number for the PPC970FX -- 100W.

Which is much higher than the numbers they gave us for Maximum Power Dissipation for either the 1.8/2.0 PPC970 which had 51W/66W Typical.

---

EDIT -- If you look here (http://forums.macrumors.com/showthread.php?p=1003470#post1003470) you'll see some more evidence of the problems IBM has been having with the PPC970 (aka, low voltage operation & reliability at higher clock speed).

Did they actually ever list the max power for the 970? I know they had 66 watts typical but I never heard any confirmed max power numbers. This graph would suggest >120 watts, but the ratio may have changed between 970 and 970fx. The lack of 0.8 volt operation also may be a reason why the iMac was delayed. If IBM does a revision of the chip that can support that it could significantly lower power consumption at low frequencies.

alexf: The chips should be identical from a user perspective. Any performance gain on the fx (minor errata fixed, stuff tweaked, whatever) will be too small to notice, if it even exists.

[alexf]

alexf: The chips should be identical from a user perspective. Any performance gain on the fx (minor errata fixed, stuff tweaked, whatever) will be too small to notice, if it even exists.

Thanks for the info.