Weird RAM Problems with my Dual G5??!!

Hello Hello
Well I recently bought a dual G5 and I just purchased the base model Dual
2GHZ that came with 512mb (2x256mb) of ram. Anyhow I recently purchased some Corsair Valu Select ram from Newegg which came in a 2x 512mb package.
So I installed them and my G5 says that I only have 1GB of Ram instead
of the 1.5 GB that I should have. I looked in the system profiler and it
says this in the memory section
DIMM0 - 256 MB DDR SDRAM
DIMM1 - 256 MB DDR SDRAM
DIMM2 - 256 MB DDR SDRAM
DIMM3 - 256 MB DDR SDRAM

I installed the 2 512mb sticks on DIMM 0 and DIMM 1.
But for some reason they are registering only 256mb.
Now I checked the box and it says they are 512mb each, i check
the label on the sticks and they say 512mb each and I also check
to make sure that it had the 8 32mb chips on each side of each stick
to maked 512mb on each stick.

Now, i also tried to have JUST the 2 Corsair 512mb sticks in the system without
the factory 256mb sticks and it did not even want to boot up.
Then I tried just the 2 Corsair 512mb sticks with one of the 256mb factory
sticks and it booted up but said I only had 512mb installed.
Its almost like if I dont have at least one of the 256mb factory sticks in there
it does not even want to boot up.

Here is the ram I got on newegg
http://www.newegg.com/Product/Produ...N82E16820145440

There is even reviews from people who have used it in their G5s and it worked.
Maybe im doing something wrong, someone please give me some advice.
Thanks

You need to have similar RAM types in each slot i.e. 4 512's, 2 256's, 4 1gbs

You can't mix and match

Yea but even if I took out the 2 256mb sticks it still wont boot up with just the 2 512mb sticks inside.

Plus ive mixed and matched Ram before with PC mother boards, but I dont know if that is the same. Anyhow I still need an answer to my post above

The PowerMac G5 needs to have it's memory always paired, and the slots are paired like this:

DIMM0 with DIMM2
DIMM1 with DIMM3

That means, if you only use two modules, they have to be either in DIMM0 and DIMM2, or in DIMM1 and DIMM3, another combination, like for example DIMM0 and DIMM1 or DIMM2 and DIMM3, won't work, your mac won't boot.

You can mix RAM sizes, though always in pairs, and paired correctly. For example in your case, that would be the two 512-modules in DIMM0 and DIMM2, and two 256 modules in DIMM1 and DIMM3.
If, like you did, DIMM0 has 512MB and DIMM2 has 256MB, the system will only use 256MB of DIMM0, to pair it with the other module.

Your problem is not mixing sizes, or wrong modules, but simply putting them in the wrong slot.

Lucky_Penguin said:

Plus ive mixed and matched Ram before with PC mother boards, but I dont know if that is the same. Anyhow I still need an answer to my post above

Click to expand...

There are also PC motherboards that needs the RAM paired...

It depends on the Mac. The PowerMac G4 doesn't need pairing, so it can take whatever size in whatever slot and will recognise it.

I thought you had to install the memory in pairs. Try placing the memory in the slots/banks DIMM0 and DIMM2. Or you can try slots/banks DIMM1 and DIMM3.

rman said:

I thought you had to install the memory in pairs. Try placing the memory in the slots/banks DIMM0 and DIMM2. Or you can try slots/banks DIMM1 and DIMM3.

Click to expand...

That's what I tried to say... :black:

Here is what Avalon is saying:

DIMM0 - 512 MB DDR SDRAM
DIMM1 - 256 MB DDR SDRAM
DIMM2 - 512 MB DDR SDRAM
DIMM3 - 256 MB DDR SDRAM

or

DIMM0 - 256 MB DDR SDRAM
DIMM1 - 512 MB DDR SDRAM
DIMM2 - 256 MB DDR SDRAM
DIMM3 - 512 MB DDR SDRAM

Avalon said:

That's what I tried to say... :black:

Click to expand...

I did not see your posts. I guess I was sitting on it to long, before I replied.

Thanks for the info, ill give it a shot and tell you what happens :dive:
I actually had this funny feeling that the slot problems were the cause
and I was planning on playing with it more, but now I know for sure.
Ok let me go power down and play with it.
Thanks again guys

O **** yeaaaaa
Ok it works now just switching the slots worked like a charm!
Thanks again!
Id buy you a beer if I saw you in public!

Lucky_Penguin said:

Id buy you a beer if I saw you in public!

Click to expand...

Cheers!

I had the same problem with my mini you know . . . .

wait a minute . . .

lol.

BEEEsH said:

I had the same problem with my mini you know . . . .

wait a minute . . .

lol.

Click to expand...

Yeah, so did I. I tried to cram 8 Registered ECC PC4000 Dimms into the Mini, For some reason it would not post after that!

:spook:

BEEEsH said:

I had the same problem with my mini you know . . . .

wait a minute . . .

lol.

Click to expand...

With the mini it's a bit different...as it has only one slot, you need to cut the module in two, in order to get them correctly paired.

dtravis7 said:

Yeah, so did I. I tried to cram 8 Registered ECC PC4000 Dimms into the Mini, For some reason it would not post after that!

Click to expand...

Hmm, I think you didn't solder them together....try that, and you'll see it will work like a charm.

PS: Before anybody that reads this starts to cut his/her memory, or solder them together: IT IS A JOKE!!

Better bookmark this, as im getting ram soom.