G5 RAM Question - mixing DIMMs

Skiniftz · Jul 30, 2004

I just got a DP2.0 off the shelf with 512Mb (2x256Mb DIMMS)

I'm just about to order my extra RAM, but need to know can I mix DIMM sizes - eg. could I install 2x1Gb DIMMS along with the 2x256Mb DIMMS and have 2.5Gb or would this cause some problem?

I can't see why it would but I seem to recall reading somewhere that if you use 1Gb DIMMS then you cant use anything smaller, however I've not seen anything to back this up.

Anyone know any better?

Macmaniac · Jul 30, 2004

Its fine to mix and math as long as the pairs of DIMMs are the same size. Having a 256 and a 1 gig stick paired together would be very bad.

Skiniftz · Jul 30, 2004

Macmaniac said:
Its fine to mix and math as long as the pairs of DIMMs are the same size. Having a 256 and a 1 gig stick paired together would be very bad.

Thanks.

slughead · Jul 30, 2004

It's off topic but I love your sig, Skiniftz

"2.5DPG5 CTO Z0AC On or before 02/08/2004" (YEAH RIGHT) - ordered 09/06/2004 01:12 PM GMT (ONE HOUR after they appeared on the UK Store)
20040730 - Ship date now put back to 20/08/04
20040730 - Had enough; bought DP2.0 off the shelf.
20040802 - Will be CANCELLING DP2.5 order.
Apple - Welcome to the consequences of keeping your customers in the dark along with stupefyingly poor customer service.

Skiniftz · Jul 30, 2004

slughead said:
It's off topic but I love your sig, Skiniftz

Heh - thankyou. Just a shame it exists really!

musicpyrite · Jul 30, 2004

Macmaniac said:
Its fine to mix and math as long as the pairs of DIMMs are the same size. Having a 256 and a 1 gig stick paired together would be very bad.

Why would that be?

And do I have to buy RAM that are sold in pairs? Like it says 1GB of RAM, but actually its 512x2.

slughead · Jul 30, 2004

musicpyrite said:
Why would that be?

And do I have to buy RAM that are sold in pairs? Like it says 1GB of RAM, but actually its 512x2.

no I don't think it has to be sold in pairs.

It's kind of like RAID 0 (striped), Dual channel uses both Ram Buses combined to make the computer faster. Therefore you need the same brand and size.

[EDIT: I bought two single chips for my PC's Dual Channel and they work just fine.. In fact, my PC crashes less than my mac does ... I'm scared.]

quarkman97 · Aug 17, 2004

We just got a refurb G5 1.6 Ghz in at work.

The G5 came with (2) 128 MB PC2700 DIMMs in it.

Mac Warehouse shipped us (1) 512 MB PC3200 DIMM.

I knew right away this wouldn't work since I needed have paired memory.

My question is: could I get another 512 MB PC3200 DIMM and pair it with the other 512 MB at PC3200?

Would this jive since once pair is at PC2700 and the other is at PC3200? IIRC, I remember reading something that the 3200 would slow to the 2700 clockspeed.

Thanks for the help in advance.

numark · Aug 17, 2004

quarkman97 said:
We just got a refurb G5 1.6 Ghz in at work.

The G5 came with (2) 128 MB PC2700 DIMMs in it.

Mac Warehouse shipped us (1) 512 MB PC3200 DIMM.

I knew right away this wouldn't work since I needed have paired memory.

My question is: could I get another 512 MB PC3200 DIMM and pair it with the other 512 MB at PC3200?

Would this jive since once pair is at PC2700 and the other is at PC3200? IIRC, I remember reading something that the 3200 would slow to the 2700 clockspeed.

Thanks for the help in advance.

Yes, you can add another PC3200 stick to the machine and have it work. The speed quoted for memory is merely its highest-rated speed. The manufacturer says it will work up to a certain speed guaranteed. You can always run it at a lower speed.

keysersoze · Aug 17, 2004

quarkman97 said:
We just got a refurb G5 1.6 Ghz in at work.

The G5 came with (2) 128 MB PC2700 DIMMs in it.

Mac Warehouse shipped us (1) 512 MB PC3200 DIMM.

I knew right away this wouldn't work since I needed have paired memory.

My question is: could I get another 512 MB PC3200 DIMM and pair it with the other 512 MB at PC3200?

I tried putting 2x128MB PC3200 in my Refurb G5 1.6 and had a tremendous number of kernel panics. The RAM worked fine in the new Dual 1.8 G5 it had been pulled from, but it screwed my machine. I will never put PC3200 in it again.

quarkman97 · Aug 17, 2004

Good to know, keysersoze. We have the 1.6 Ghz as well. I've read a little bit while doing a search for this about all the memory problems with the original G5's.

I'll send back the 512 and get two, 256's.

keysersoze · Aug 17, 2004

quarkman97 said:
Good to know, keysersoze. We have the 1.6 Ghz as well. I've read a little bit while doing a search for this about all the memory problems with the original G5's.

I'll send back the 512 and get two, 256's.

and make sure they are the PC2700...

quarkman97 · Aug 18, 2004

Well, sorta bad news.

The boss already ordered a PC3200 512 MB stick and it should be here today.

I told him that it would be risky, but he said do what you gotta do. If it's cranky, we'll order two PC2700 DIMMs.

I'll keep an eye on it and post my results here.

<crosses fingers>

garybUK · Aug 18, 2004

G5's are REALLY funny about what ram you put in, i've tried corsair and kingston with really bad Kernel Panics.

The only stable ram I have been able to get it working with properly is Crucial and Samsung's. I always recommend buying them in pairs, Crucial.com/uk will ship x2 of the identical ram, i put x2 512mb's PC2700's in my Dual 1.8 along with the stock samsung x2 256mb's PC2700's

keysersoze · Aug 18, 2004

quarkman97 said:
<crosses fingers>

Please do let us know how it turns out. My case could be isolated- it would be nice to be proved wrong. Things you should watch out for:

1) Computer freezing up needing a hard reboot
2) Grey screen appears that needs a hard reboot
3) Non-responsive keyboard/mouse

Good luck

keysersoze · Aug 18, 2004

garybUK said:
G5's are REALLY funny about what ram you put in, i've tried corsair and kingston with really bad Kernel Panics.

The only stable ram I have been able to get it working with properly is Crucial and Samsung's. I always recommend buying them in pairs, Crucial.com/uk will ship x2 of the identical ram, i put x2 512mb's PC2700's in my Dual 1.8 along with the stock samsung x2 256mb's PC2700's

I thought all Dual 1.8's took PC3200? Am I wrong?

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