2.7DP G5 memory issue???

[theMarble]

So my G5 physically has 4.5GB of RAM in pairs (2x 256MB, 4x 1GB) however only 2.5GB is detected in OS X. I figured out that my "Rendition" branded memory (Pair 3 - 2x 1GB) wasn't working. So I tried each DIMM in my iMac G4 1.25GHz and it booted up fine. What could be the problem here?

 

[B S Magnet]

So my G5 physically has 4.5GB of RAM in pairs (2x 256MB, 4x 1GB) however only 2.5GB is detected in OS X. I figured out that my "Rendition" branded memory (Pair 3 - 2x 1GB) wasn't working. So I tried each DIMM in my iMac G4 1.25GHz and it booted up fine. What could be the problem here?

By chance, are you mixing pairs of ECC memory with non-ECC?

 

[Dronecatcher]

Maybe cracks in the solder of the slots - I had a DP G5 that would gain 2Gb once it got hot!

 

[theMarble]

Maybe cracks in the solder of the slots - I had a DP G5 that would gain 2Gb once it got hot!

Hmmm. I've had it on for about a week, sometimes 24/7 and it doesn't make a difference. I will try putting the 3rd pair in Slot Pair 4.

 

[Dronecatcher]

Hmmm. I've had it on for about a week, sometimes 24/7 and it doesn't make a difference. I will try putting the 3rd pair in Slot Pair 4.

I'm not suggesting yours would have the same behaviour, just that the RAM area is fragile - I had another DP that after a round of RAM switching and replacements lost it all and never recovered.