memory upgrade problem on dual G5...

kenny

kenny

Registered
So, I'm the proud owner of a dual 2.5 G5 tower, which I want to upgrade the memory in. I got these two 1GB sticks that no matter how many times I'd reseat them, MacOSX would never see the extra 2GB of memory. It does see the existing 1.5GB worth of DIMMS correctly, and shows the slots with the new ones as "empty". Then, I did some poking around Google, and found how to query OpenFirmware on what it sees, and it clearly saw the extra 2 sticks (6 in all):

Code: 
[FONT=Courier New]0 > dev /memory .properties 
name                    memory
device_type             memory
.
.
.
(more detail than anyone's probably interested in..)
.
.
.
dimm-types              DDR SDRAM
                        DDR SDRAM
                        DDR SDRAM
                        DDR SDRAM
                        DDR SDRAM
                        DDR SDRAM
                        
                        
dimm-speeds             PC3200U-30330
                        PC3200U-30330
                        PC3200U-30440
                        PC3200U-30440
                        PC3200U-25440
                        PC3200U-25440
                        
                          
ram-layout-architecture 00000001 
ram-bus-width           00000080 

 ok
0 > [/FONT]

Then I plugged the "PC3200U-25440" (since that corresponds to the two new sticks) in Google, and found a couple of threads that discuss how the "25" (or "30") is an indication of CAS timing (2 vs. 3), and that the G5 can only run as CAS 3, and I'm feeling pretty doomed as a result.

So, are there any tricks to making the CAS2 (which is apparently faster, according to what I've been able to find) work in my G5?

Or, did I just burn a pile of money on DIMMS I can't use even though they are PC3200? Any ideas how to tell what they are before walking out of the shop with them?

Thanks..
 
"Or, did I just burn a pile of money on DIMMS I can't use even though they are PC3200? Any ideas how to tell what they are before walking out of the shop with them? "


Yeah, you have to really watch it when buying DIMMS for the G5. The DIMMS for my G5 1.8 duel are different than those for the 2.xGhz G5's. Might go out to crucial.com / or kingston and go through their memory chooser to find out which of the dimms are the wrong ones.


good luck.
 
You need to make sure that all the specs are the same as what apple specifies. Crucial says that you need CL=3 2.6V non-ecc unbuffered ram.

I put in 2 512 sticks from crucial when I bought my G5. All the sticks in the machine register as PC3200U-30330

Do you have 3 different types of ram in there?
 
Yeah, there are (were) three different types on-board, with the "PC3200U-25440"s being the problem... I even went so far as to pull the existing RAM, and put those two in by themselves... I didn't even get a startup chime. Plus, the power LED on the front was doing what looked like a "blink code" of what was wrong (3 blinks)... This has been a bit of education in the memory technology (didn't know about the critical timing issues for the G5) and OpenFirmware (for querying what it sees), so it's not a totally wasted effort..

Guess I'll get to test the return policy at the shop where I got these later...

Thanks guys!
 
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