Only seeing 1GB RAM...help, why?

[ted400]

I have an older Mac Pro (G5 Dual 1.8's)...The problem is I have four sticks of 512MB installed however when I look at "About This Mac" only two sticks show up in slots 1 and 2. I have all the same make/model of RAM and have even tried to move the sticks around into different slots, still same thing slot 1 and 2 are the only one's recognized. Slots 3 and 4 say they are "Empty" when in fact they are occupied with the same RAM as 1 and 2.

...I know this configuration is a little "light" for the Pro standards these days, but this is my file server and doesn't require a ton of overhead, I'd just like to get it running a bit faster, and instead of getting two 1GB sticks I'd like to figure out why the 2GB I have in there don't work.

...ideas?

 

[gugucom]

A Power Mac dual CPU needs pairs of RAM on both RAM banks A and B. The RAM slots need to be filled from the inside to the outside with equal pairs.

 

[ted400]

A Power Mac dual CPU needs pairs of RAM on both RAM banks A and B. The RAM slots need to be filled from the inside to the outside with equal pairs.

Right, I have the same RAM in every slot, its the same make model and size so they are "paired".

 

[wpc33]

When that happened to me, with 4x1GB in a G5, and 2GB showing, I rotated the sticks to troubleshoot. When that didn't fix it, I found the one or two that were to blame, and RMA'd them to OWC. The replacements worked immediately.

 

[ted400]

When that happened to me, with 4x1GB in a G5, and 2GB showing, I rotated the sticks to troubleshoot. When that didn't fix it, I found the one or two that were to blame, and RMA'd them to OWC. The replacements worked immediately.

Hmm...good call. I'll Tech Tool and see if I have a bad stick in there. Just the bump in the right direction I was looking for.