Power Mac G5 not recognizing all RAM

Hello all,

I recently decided to upgrade my G5 RAM from 2GB to it's full capacity (8GB). This is the model I have Power Macintosh G5 2.0 DP (PCI-X) Specs (Power Mac G5, M9032LL/A, PowerMac7,2, A1047, 1969) @ EveryMac.com I ordered from Memory Upgrades | 4AllDeals.com using their memory upgrade page which lets you select via computer manufacturer, model, etc. I had 2GB already installed so I purchased a 4GB kit and a 2GB kit System Details For Your Power Mac G5 (Dual 2.0 GHz) | 4AllDeals.com making a total of 8GB including the 2GB I already had installed. It should be noted that the 2 already installed were also purchased previously from 4alldeals using their memory upgrade page. Now onto the issue I am having - The RAM was all installed properly in matched pairs of 2 from the center outwards but for some reason the DIMM4/J41 and DIMM5/J42 slots are only recognizing half of the ram. http://i.imgur.com/22Ol0Vsl.jpg

Does anyone know what might be causing this? I tried resetting my nvram after installing and moving the sticks around whilst keeping them in pairs. They are all 1GB sticks so it shouldn't matter which pair is in which slot. But the computer continues to only show 7GB as being installed in those slots. Here is what the diagnostics page shows http://i.imgur.com/wTg2qwSl.jpg

Any help would be much appreciated. Thank you

Welcome to the Mac-Forums.

You've received some bad modules. Send them back and get new ones in exchange. We usually only recommend buying memory direct from Crucial or Other World Computing (Mac Sales).

chscag said:

Welcome to the Mac-Forums.

You've received some bad modules. Send them back and get new ones in exchange. We usually only recommend buying memory direct from Crucial or Other World Computing (Mac Sales).

Click to expand...

Thanks for your reply. I thought that was the problem at first so I tried switching all of the modules around so that the other 6 were at one time in those 2 problem slots but every time I tried with a different pair they were still only recognizing half of the ram. I actually ordered another 2GB from OWC just last week and it came in today OWC 2.0GB PC3200 DDR400 Matched Pair Kit (2x 1GB)... in stock at OWC and alas, even after installing properly in those slots and resetting the nvram, the problem persists. Those 2 slots are only reading half of the ram.

OK, understand. Buy a can of compressed air and blow a couple of short blasts into those slots to see if it clears away any dust or debris. There's really no easy way to clean module slots without possibly damaging them. I remember a slot cleaning tool that was available back in my old PC days but slots in those machines were much more durable than those of today. Just be careful doing any cleaning.

It's a wonder I hadn't thought of that already. I actually have a can of air on hand. I will try it and report back. Thanks

Cleaning the slots with compressed air doesn't seem to have done anything. So I am guessing this is in-fact an issue with the slots themselves and does not have anything to do with the RAM type or OS X. One thing I should mention though is I did a reinstall of Leopard with the fully loaded RAM (all 8GB installed) even when it was only showing 7GB and upon checking my configuration after the clean install it was showing 8GB in the system profiler and activity monitor. This was when I was using all of the same RAM from 4alldeals. But as soon as I restarted the computer it was back to only showing 7GB and I was getting the same error in the diagnostics page. Also, when I put a 1GB configuration (2x512MB) of Kingston RAM I ordered a couple years ago into those 2 slots, it shows up as 512 MB. So it seems that either both of those slots are only recognizing half of what is installed or one of the slots is not recognizing anything at all. Any further ideas on how I might be able to solve this issue?

Any further ideas on how I might be able to solve this issue?

Click to expand...

No, not without going through a lot of expense. If your PowerMac G5 is otherwise working OK, I would just leave well enough alone and go with the 7 GB. That is strange though that it's recognizing those 2 modules as 512 MB each. You can always dig around eBay for a used logic board for your machine but even swapping out the current board is no guaranty that you won't pick up other problems, notwithstanding all the work changing out the board.

I just looked up the specs on your machine. According to Mactracker, it's a 2003-2004 model (one of the first PowerMac G5 machines). This is what they say about the memory:

Maximum Memory 4.0 GB (1.6 GHz) or 8.0 GB (1.8 GHz+)
Memory Slots 4 - PC-2700 (1.6 GHz), or 8 - PC-3200 (1.8 GHz+) 2.5v, unbuffered, 8-byte, nonparity 184-pin DDR SDRAM (matched pairs)

I'm sure you have the right modules otherwise it probably wouldn't even boot.

I bought this machine used on eBay around '06-'07 and it has performed extremely well for me considering how long I've had it. If I wasn't so OCD I would have gotten over the RAM issue a while ago. I'm thinking about stepping up to a newer intel based mac in the near future anyways. Thanks for all of your help.

A very wise idea, at this point.