I own 8 gig (4 x 2Gig) of Crucial Dominator PC2-8500 ram
 
http://www.overclockers.co.uk/show [...] =MY-148-CS
 
with 4 gig in, the system is stable (although running at loose timmings of 5-7-7-24 which is claims to be it's defaults!!)
 
but when i add the 2nd 4 gig the system becomes incredibly unstable and wont prime95 / orthos for more than a few seconds
 
I was wondering if anyone had any ideas of how to fix this, or what can be done????
 
I am running this on a gigabyte GA-P35C-DS3R, Core 2 Duo e6600 oc'd to 3.2.
 
PLEASE HELP
 
A.

Did you ever update the Bios?  Gigabyte released new versions recently that say they correct memory instability, however,  I don't know if it pertains to 4 module stability.
 
Edit: Hmm...I just checked your board and it looks like there aren't any recent bios updates that help correct the memory stability.  Your problem is a common problem though.  Usually people have to stick with two modules.  

Yes i am running the latest bios (F10 for my board)
 
I have stress tested every chip and on their own or dual channeled they are fine. it's just when they're all in the motherboard together then i have a huge problem  
 

 
A.

what voltage are you running the memory at? usually the "default" settings that are advertised run at 2.1v or even 2.2v.  i believe the corsair dominators run at 2.1v.

I'm running at 2.1, although the ram ram being under volted wouldn't explain the 8 gig problem would it?
 
A.

if the ram is underpowered, then it is possible that it could lead to instability. but since the sticks work in pairs, then that might not be your problem.  
 
i noticed your system is overclocked. have you tried running everything at stock speeds? if everything runs fine with 8gb at stock speeds, then you might be hitting a barrier as far as overclocking your system is concerned with 4 modules.
 
you could also try kicking up the northbridge and/or cpu voltage while overclocked, to see if that helps with stability

You may need to increase the northbridge (MCH) voltage a little.

I once read on a manufacturer response to NewEgg comment that the default settings the manufacturer mention for dual kits is for the 2 modules only, not 4 so you might have to play with speed and settings a bit. You could also try to ask Corsair support, they might know just the right thing.

Agreed. Also increase DDR2 voltage.

wow. sad answers. If you read some of the previews on the net (including one here on toms about 8gb ram), you'll notice some motherboards FAIL using all the memory slots. It can also be memory that is NOT the same as the original (need to be the same type/speed/settings). Or even just bad memory. try two sticks at a time, run benchmarks/burnin programs. If no failure on any, then try the 4 at a time, and rearrange a few times retesting until it can pass. If it never passes with the 4 installed, that's most likely bad motherboard (as toms and other sites noted a few boards have this issue).

 
Hmm...sad that you didn't read through the entire thread.  
 
 
 

^ Agreed. Please read CAREFULLY before posting.

Yes.
When you add more memory chips it adds more load to the voltage regulators for that line.
 
Think of overclocking and PSU's.
Most people need to raise volts when they overclock...becuase the PSU is not -really- that good and raiseing the voltage lets the currant flow to the parts (never had to boost voltages with a PC Power & Cooling and my systems all have a 50% OC).
 
Kick up the power about 2% on the ram voltage and retest.

Thank you for the help everyone.
 
I have tried raising voltages but still no luck.  
 
Unfortunately I have decided to simply return the 2nd 4 gig set and live with 4 gig.
 
Oh well
 
A.

Had the same issue.  Upping memory and mch voltage didn't help.  What do you have your memory ratio set at?