PowerMac G5 RAM issues

[zackkmac]

So I bought an 8GB 8x1GB set of Crucial RAM off eBay for my PowerMac G5 Dual 2.0GHz on eBay and it may be faulty, but I just want to see what you guys think first before I email the seller.

When I first removed the 4 256MB sticks already in the PM, I put in all 8 sticks. Booted the computer, no chime, and it tried to load but would either freeze at boot or load OS X but instantly kernel panic.

So then I removed one stick and the PM booted fine. I opened System Profiler, and then it showed 2GB RAM installed which was very strange because 7GB was installed. The "Memory" section showed 4 slots (DIMM 0, 1, 4, and 5) to be empty, while the other 4 showed to be 512MB...which I found to be very odd. I know that can happen with high-density RAM but this was advertised and shows up as low-density on google.

Anyone know what else I should try? Memtest says I have 1064MB of available RAM.

BTW, the RAM is 8 sticks of CT12864Z40B.

 

[RedCroissant]

So I bought an 8GB 8x1GB set of Crucial RAM off eBay for my PowerMac G5 Dual 2.0GHz on eBay and it may be faulty, but I just want to see what you guys think first before I email the seller.

When I first removed the 4 256MB sticks already in the PM, I put in all 8 sticks. Booted the computer, no chime, and it tried to load but would either freeze at boot or load OS X but instantly kernel panic.

So then I removed one stick and the PM booted fine. I opened System Profiler, and then it showed 2GB RAM installed which was very strange because 7GB was installed. The "Memory" section showed 4 slots (DIMM 0, 1, 4, and 5) to be empty, while the other 4 showed to be 512MB...which I found to be very odd. I know that can happen with high-density RAM but this was advertised and shows up as low-density on google.

Anyone know what else I should try? Memtest says I have 1064MB of available RAM.

BTW, the RAM is 8 sticks of CT12864Z40B.

I would advise you to load the original RAM that you had back in it and then put the other RAM modules in until the slots are full. The restart the machine and once it's restarted, open System Profiler again and open the Diagnostics section to see which RAM modules failed and remove those.

What does the label on the RAM say? If there is no label on it, then email the seller and return it.

 

[zackkmac]

I posted the model of the RAM in my OP. It's CT12864Z40B.

So I tried loading just the original RAM into 4 consecutive slots and it wouldn't boot. The sleep light blinked twice. Tried the same with Crucial sticks and got the same results. I also tried putting just one 256MB stick in at a time, going through all 8 slots, and got the two blinks/no boot. Tried the same with the Crucial sticks, 1GB at a time, nothing.

Then I put all 8 Crucial sticks in, which originally would cause it to boot but get a kernel panic, and this time it booted fine. But, System Profiler shows it to have 1GB total (two 512MB sticks) and Diagnostics shows the start up test result as Failed and listed all 8 RAM slots.

I am now in Single User Mode running memtest with all 8 1GB sticks in (this thing is loud!), and it shows it to have 2951MB available.

To me it seems more like the PM is having issues instead of the RAM itself but I don't know..

 

[zackkmac]

I let memtest run in Single User for a few hours. Now after booting into OS X, the computer sees 3GB. Two sticks now show as 1GB each and then 2 other sticks show up as 512MB.

DIMM0, DIMM1, DIMM6, and DIMM7 still show as Empty. And DIMM4, DIMM5 are the ones that see 512MB rather than 1GB. Based on this and my OP, DIMM 2 and 3 seem to be working fine. Btw, how do I tell which slots are which when looking at them?

I've been seeing something about taking a heat gun to the PM for issues like this - will a hair dryer work, and what exactly is the process (and why)?

 

[havokalien]

Heat gun

You take the board out and your are actually re flowing the solder on the ram slot connectors. Flexing of the board from heat in use and no lead in solder anymore made them weak. The hair dyer trick is a test to see if the ram slots will show up in profiler to show that is the problem (sometimes flexes the board enough to work,sometimes it doesn't). Hope that helps you.