Test your iMac G5 for a 64 or a 128 bit memory bus (and why is mine 64 bit?)

[Lancetx]

What about a single module?

Ok, along these same lines here's another hypothetical question. I have a friend that is getting an iMac G5 soon and needs a total of 512MB for his needs. Would he be better off with 2 matched 256MB modules or a single 512MB? Obviously the memory bus would be 128 bit with the two matched 256MB modules, but will the memory bus be 64 bit or 128 bit when using a single module only? To put it simply, would using two matched 256MB modules be faster than using a single 512MB would be?

 

[Elan0204]

Ok, along these same lines here's another hypothetical question. I have a friend that is getting an iMac G5 soon and needs a total of 512MB for his needs. Would he be better off with 2 matched 256MB modules or a single 512MB? Obviously the memory bus would be 128 bit with the two matched 256MB modules, but will the memory bus be 64 bit or 128 bit when using a single module only? To put it simply, would using two matched 256MB modules be faster than using a single 512MB would be?

Since matched 256MB modules would let the memory bus run in 128 bit mode, it should be faster than a single 512MB module running in 64 bit mode. However, Apple doesn't sell a 512MB 2 DIMM option, so getting mached 256MB DIMMs could be problem.

 

[Jovian9]

I wish I could drop 2 matching 1gb sticks in but the wife doesn't like that $500 dollar idea. Imagine that.

My situation exactly!!!

I'm in the same boat too. Not sure whether or not to get a 1GB stick to go along with the Apple 512 or get another Apple 512.....or order 2 512's from Crucial. I do lots of video editing and my wife dabbles in web design and uses the Macromedia suite and Photoshop a lot.
So is 1GB @ 128bit better than 1.5GB's at 64bit? The question lots of people are waiting to here answered...........

 

[slooksterPSV]

I'd get the 1GB and wait till you have the money to buy another 1GB 128-bit.

 

[continuum]

i just ran the script and it said 128 bit. I have the OEM apple memory (256k) plus the 1gig memory I added two months ago.

 

[Jovian9]

i just ran the script and it said 128 bit. I have the OEM apple memory (256k) plus the 1gig memory I added two months ago.

I'm assuming you're talking about a PowerMac G5, right? B/C 2 months ago there was no iMac G5.

Would there be a difference with this RAM issue b/t the 1.6GHz PM G5 and the new iMac G5's?

 

[continuum]

I'm assuming you're talking about a PowerMac G5, right? B/C 2 months ago there was no iMac G5.

Would there be a difference with this RAM issue b/t the 1.6GHz PM G5 and the new iMac G5's?

yes powermac. 1.6ghz G5

 

[coconn06]

yes powermac. 1.6ghz G5

It's nice that your PowerMac is running with 128 bit memory, but that's irrelevant to this conversation, as we're talking about the new iMac.

 

[continuum]

my apologies. i now realize that. i can contribute that i bought crucial ram that was much cheaper than apple ram as a previous post said the pricing was similar.

 

[slooksterPSV]

Thats good, hey be sure to check http://www.mwave.com to see if they have their brand of RAM cheaper.

 

[oldpismo]

At the bottom of the page of the developer notes it has a table showing the various DIMM configurations that can be used. Would it be these that have to match do people think?

i.e. both memories need to be 16M x 16 x 4 in order to get the 128 bit.

If this is the case can someone tell me the memory configuration of the Apple 512MB ram, as I have ordered 512 apple ram, and was just going to upgrade it with another 512, but now it looks like I need to be more careful.

I would offer to swap with you Elan, but I live in the UK, so I don't think it is very practical.

Peter

 

[Jovian9]

According to this Apple Discussions page:

http://discussions.info.apple.com/webx?14@151.3qntavMSxCj.1@.689b8b40

Someone purchased a 256MB stick of Samsung RAM and paired it with the stock 256MB of Apple RAM producing the desired 128bit pairing.

The only place I was able to find Samsung RAM was here:

http://www.18004memory.com/category.asp?catid=9&subcatid=911

And they have it listed so that you have to buy 2 512MB sticks (no option for one).

If anyone can get a hold of a Samsung 512 stick to test it with your Apple 512 stick, please post the results here.

 

[Jovian9]

Oh yeah, I have bought RAM from the site I just listed above (for both of the G4 iMacs I had) and had zero problems. The first was a generic 512MB stick on my 15" 800MHz Superdrive G4 iMac.....the 2nd was a hyperspeed memory 512MB stick on my 17" 1GHz Superdrive G4 iMac. They worked flawlessly.
...just in case anyone is considering buying from them.

 

[MacinDoc]

My situation exactly!!!

I'm in the same boat too. Not sure whether or not to get a 1GB stick to go along with the Apple 512 or get another Apple 512.....or order 2 512's from Crucial. I do lots of video editing and my wife dabbles in web design and uses the Macromedia suite and Photoshop a lot.
So is 1GB @ 128bit better than 1.5GB's at 64bit? The question lots of people are waiting to here answered...........

Someone posted Xbench results on one of these forums that showed 2 matched 512 MB DIMMS got better scores than mixed 1 GB and 512 MB sticks, in spite of the fact that the matched DIMMs added up to less RAM.

 

[Mav451]

Would having the same exact type of RAM upgrade performance on a PC. We have so many different kinds... what the heck am I talking about, screw the PC, I'm moving to Mac ppl.

This is just too hilarious. I see another post about "hidden timing" issues.

You can mix and match as long as the RAM is capable of running at the same speeds. I.e., don't get cas2.5 and cas3 RAM, since I have no idea how you change RAM timings on a Mac. By SPD, the 2.5 will run faster, but it would have to slow down to the cas3. Again, I have no idea how you get to BIOS settings to make sure this doesn't happen.

The other solution is to simply get cas3 RAM in the first place.

 

[Sun Baked]

yes powermac. 1.6ghz G5

The PowerMac G5s are all 128-bit -- it is a requirement of the dual-channel memory controller -- if you don't put in matched pairs of memory you risk running into problems.

The iMac G5, dropped the 128-bit requirement, something that was expected due to the scare realestate on iMacs/consumer machines for using dual-channel RAM.

They couldn't afford the space for 4 DIMM slots on a iMac, so dropping back to single-channel memory to lop off 2 DIMM slots was the expected design decision.

---

aka, stick to the topic, it's iMac G5s.

because if you're getting 64-bit on a PowerMac G5, something is wrong -- and deserves it's own "Something is wrong with my PowerMac" thread.

 

[MacG]

Crucial worked for me

It seems that Apple is sourcing multiple vendors for its RAM.

I just got my 20" iMac today (love it BTW) and it came with 1 512MB stick. I got a second 512 from crucial and the system reports 128bit access.

The Apple OEM stick was:
Hynix
PC3200V-30330
512MB DDR 400MHz CL3
HYMD264646B8J-D43 AA

The Crucial that I put it was:
512MB 184-PIN DIMM 64Mx64 DDR 3200 Unbuffered

These two chips matched!

GB

 

[Elan0204]

It seems that Apple is sourcing multiple vendors for its RAM.

I just got my 20" iMac today (love it BTW) and it came with 1 512MB stick. I got a second 512 from crucial and the system reports 128bit access.

The Apple OEM stick was:
Hynix
PC3200V-30330
512MB DDR 400MHz CL3
HYMD264646B8J-D43 AA

The Crucial that I put it was:
512MB 184-PIN DIMM 64Mx64 DDR 3200 Unbuffered

These two chips matched!

GB

When you opened up your iMac did you notice if the Apple supplied chip had the little memory chips on one side or on both? What about the chip you received from Crucial?

 

[VooDooPope]

It seems that Apple is sourcing multiple vendors for its RAM.

I just got my 20" iMac today (love it BTW) and it came with 1 512MB stick. I got a second 512 from crucial and the system reports 128bit access.

These two chips matched!

GB

Guess I'm going to have to crack my iMac open and find out what is inside before buying that next 512.