PowerMac Dual 1.8 G5 Question......

[Mac2004]

What are the main differences between the old Powermac G5 dual 1.8 ghz (rev A model) and the new PowerMac G5 dual 1.8 ghz (rev b model)?

I'm curious because it looks to me like the old dual 1.8 has a bigger hard drive and memory.

Is there anything I should be concerned about when buying the old dual 1.8 versus the new one? Has anything been tweaked or updated? Please let me know which one I should buy...... Is the G5 chip the same or is it different and are their any heat or fan issues with the old model?

[nyassa3898]

there is a difference, the old g5 dual 1.8 had 8 ram slots, the new machine only have 4 slots. the hard drive is the same i believe oh and the optical drive should be an 8x now

[JOD8FY]

Is the G5 chip the same or is it different

The current G5's use a 90nm processor whereas the older ones used *I think* 910nm chips. I got bashed around for screwing this one up before - I hope I've cleaned up my act :D. I know the current G5's are 90nm.

JOD8FY

[ChrisFromCanada]

the new ones are exactly like the old 1.6 except dual processors and 90nm. BTW is was 130nm before (i'm pretty sure). To summarize the differences:

-no PCI-X slots (if you don't know what these are then don't worry about it)
-smaller HD
-4 RAM slots

thats it.

[Sun Baked]

The other machine had a PCI-X capable chipset, the new one does not.

Apple deleted the Hypertransport PCI-X Tunnel chip on the RevB DP1.8PM and is using the PCI bus on an updated KeyLargo2.

The SP1.6PM still had the Hypertransport PCI-X Tunnel chip, but it was crippled (software or resistor settings) to only run at PCI speeds -- the capability is there if someone could re-enable PCI-X.

You can't do that on the RevB DP1.8PM, since the KeyLargo2 is most likely not PCI-X capable.

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There is also the chance that this will affect PCI operation, since all the I/O (besides AGP & memory) is now possibly on a single PCI bus -- at least it's all on the same chip. No public info on the inside of the chip.

[Mac2004]

Well I still do not have a clear answer what the better one to get is (old 1.8 or new 1.8)????

[Sun Baked]

Well I still do not have a clear answer what the better one to get is (old 1.8 or new 1.8)????The biggies...

The both use the same 130nm PPC970.

The new one has few DIMM slots.

The new one has a downgraded PCI bus, and there is no chance ever of finding a way to overclock it -- most likely.

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If you don't care about the PCI situation, then your choice will most likely be default configuration and DIMM slots.

[Dr. Dastardly]

Why did they downgrade it? I can see that if they didn't it would be to close to the dual 2's and everyone would eat up the 1.8 with the $500 savings so thats not the question. My question is how come the line up isn't more like 1.8, 2.2, and 2.5. Everything the same specs except the processor and I think the space between the processor gaps would justify the price jump from system to system. And 2.2 doesn't seem like a huge R&D jump from 2.0 seeing that they already have a 2.5. Granted it needs liquid cooling it is still 300 megahertz less.

[Sun Baked]

Why did they downgrade it?There is the chance (purely speculation mind you) that the RevB DP1.8PM will be taking the same type of space as the PowerBook 12 in the Power's desktop line.

The change they made is quite odd when they really didn't need to put the low-end onto a modified motherboard platform -- unless like the PB12, there was a reason to. ;P

As far as the speeds, maybe they didn't have the 90nm processors ready. They did stick with the 130nm on the 1.8 & 2.0 PM.

[Dr. Dastardly]

There is the chance (purely speculation mind you) that the RevB DP1.8PM will be taking the same type of space as the PowerBook 12 in the Power's desktop line.

The change they made is quite odd when they really didn't need to put the low-end onto a modified motherboard platform -- unless like the PB12, there was a reason to. ;P

As far as the speeds, maybe they didn't have the 90nm processors ready. They did stick with the 130nm on the 1.8 & 2.0 PM.
I thought they were all 90nm. 1.8, 2.0, and 2.5.

[Sun Baked]

I thought they were all 90nm. 1.8, 2.0, and 2.5.Nope... people are still waiting on their low volume 90nm XServe G5s. :rolleyes:

It tested out as 130nm, still haven't seen a reliable report of a 90nm in the new Rev B 1.8/2.0 PM -- people keep pointing to Apple marketing poop, instead of PVR checks.

[Mac2004]

Well I think I will be buying the older version of the dual 1.8 PowerMac G5 tomorrow. The store that I was at yesterday has 2 left and the salesperson told me they are a better deal than the old (rev A mode;) PowerMac G5 dual 1.8. I sure hope that's correct and there haven't been any major changes in the rev B models. The old 1.8 is only $50.00 more than the new 1.8 rev B model and you get double the hard drive space and double the memory.

[ddtlm]

Dr. Dastardly:

My question is how come the line up isn't more like 1.8, 2.2, and 2.5. Everything the same specs except the processor and I think the space between the processor gaps would justify the price jump from system to system.
Actually I figure they did this for two reasons:

1) They probably did not want to clock the 130nm 970 at 2.2ghz (heat?), and did not want to increase demand for the 90nm 970.

2) As you can see on Apple's PR benchmarking page, in many cases performance scales rather linearly from 1.8 -> 2.0 -> 2.5. I've been telling people that the system controller is probably a latency pig (slow request turn around time) and is probably becoming a performance bottleneck. Certainly, the FSB design does not appear to lend itself to low-latency since its messages need to be translated and buffered to talk to RAM. Good P4 chipsets tend to run the FSB at the same address clock (base clock) as RAM (ex: 4x200 = 800mhz FSB, 2x200 = DDR400 RAM) which helps get things through without delay.

So, I believe, Apple had to leave a large clock speed gap in order to make the 2.5ghz machine worth it. http://www.apple.com/powermac/performance/

[BrianKonarsMac]

The current G5's use a 90nm processor whereas the older ones used *I think* 910nm chips. I got bashed around for screwing this one up before - I hope I've cleaned up my act :D. I know the current G5's are 90nm.

JOD8FY

man...910nm!? thats one fat chip. it was 130nm. :p the new chips run cooler...but the new dual 1.8 uses a crippled motherboard (the same one on the single 1.6). get a old dual 1.8 or new dual 2.0. 2.5 would be fun just to see the liquid cooling...kind of like the backlit keyboards, just makes you feel special :rolleyes:

[mojohanna]

Well I think I will be buying the older version of the dual 1.8 PowerMac G5 tomorrow. The store that I was at yesterday has 2 left and the salesperson told me they are a better deal than the old (rev A mode;) PowerMac G5 dual 1.8. I sure hope that's correct and there haven't been any major changes in the rev B models. The old 1.8 is only $50.00 more than the new 1.8 rev B model and you get double the hard drive space and double the memory.

Keep in mind that the optical drive is an 8x dvd burner vs the 4x. this may or may not be a big deal depending on how you use the machine. You do get double the HDD capacity on the old model, however, it is cheaper to add a 2nd HDD than it is to upgrade to an 8x DVD burner.
I struggled with the same decision and went with the newer version. Big step up from a G4 450. I'm lovin it....

[Mac2004]

You also get double the memory in the old PowerMac G5 1.8 (512MB)