Problems installing new RAM in Mac Pro - HELP

[ndriver182]

I just received 4 (2x2 gig) gigs of new OWC 667mhz RAM and almost immediately ran into problems after installation. My goal was to use the 4 gigs of new RAM with the existing 1 gig that came with the machine (2x512 meg). I tried to follow the below diagram as closely as possible, more specifically, Figure 5C for 5 gigs.

I swapped the two 512 sticks to the second empty riser since the diagram shows that the stock 1 gig configuration from apple has the two sticks on the first riser. Then I installed the 4 new gigs in the positions where the original RAM was.

I *thought* everything was fine when I installed the new RAM. The computer booted up and my "about this mac" screen showed 5 gigs. I walked away from the computer for about 2 minutes and in the other room I heard something that sounded like a plane taking off (figuratively of course). I came back to find that the intake fan on the MP was going full tilt! I've NEVER heard that happen before. My screen also had a semi-transparent black bar across the top 1/3 of the screen. I immediately shut down the computer via holding the power button down since the computer was frozen.

I gave turned on the computer and tried again. Again a couple minutes later my screen went dark as if the computer had gone to sleep, but it had only been a couple minutes.

I just pulled out the memory and put everything back to normal and now the computer seems to be working properly again. Is it possible that I installed the RAM in the incorrect slots? Is the computer unstable when running a strange amount of RAM like 5 gigs? I know the RAM was seated completely and so were the risers.

Sorry for such a long post, but I'm hoping it's not bad RAM and just a case of "operator error"

RAM Configuration Diagram
http://att.macrumors.com/attachment.php?attachmentid=82929&d=1187657852

 

[ndriver182]

I may have answered my own question. Go figure. I found an installation video on the OWC website and it says to install new memory next into riser B directly, which is completely NOT what I did. I'm hoping following the instructions *who'da thunk it* would be a smart thing to do. Hopefully this works.

 

[bob5820]

Is it possible that I installed the RAM in the incorrect slots? Is the computer unstable when running a strange amount of RAM like 5 gigs? I know the RAM was seated completely and so were the risers.

http://att.macrumors.com/attachment.php?attachmentid=82929&d=1187657852

I do think that it really matters which slots you use as long as you use matched pairs. Their may be a slight performance benefit to using one configuration over another, but I don't think that it would cause a failure. I'd say the most likely problem is the RAM was not fully seated, either that or the RAM is bad. Reseat the RAM, if it boots up with 5GB's and looks stable, run a memory test (Google OS X memory test) a few loops.