Asus P5E3 crash with 2 GB

Hello everyone.
So now after hours and hours of research (and for 3 months), I give up and ask for your help.

The problem is that with 2GB of RAM my PC crashes anytime, but especially when it imposes a little effort ... whereas with 1 GB it would never plant!

Current configuration:
Antec three hundred
Antec EarthWatts 430
Asus P5e3
CPU Intel C2D e8400
2GB RAM Corsair DHX xms3 (or rather 1 GB at the moment :) )
Ventirad Zerotherm cf900
Twintech 8800 GT heatpipe
Seagate Barracuda 250 GB SATA II

Desired configuration:
Power Supply Corsair 650W or 750W
Double hd4850 or ATI hd4870 (it depends on the performance and the discount seller :ange: )
Noctua NH-U12P

So now the problem is that before buying all this, I would run with 2GB of RAM. I received my box a few days ago and two fans Noctua NF-P12 and compared to my old box advance krysto aeration is optimal. So I noticed that my 2 GB of RAM worked as ever and the PC has crashed several hours later (or closure of application is the worst blue screen, it's always like that). Unfortunately I can not verify the hypothesis of overheating because I returned my two noctua "s" for exchange with two Enermax "s" magma.

So here I am open to all solutions except go to the computer store...

THANK YOU!

PS: memtest made perfect result and a 100% ... problem in XP and Vista ...

You tested your ram with memtest 86?

yes I made lots of test ... and there would be no problem.

You tested your sticks to other sites (eg 2 and 4 instead of 1 and 3).
There may be a faulty slot, although this is rare.
Did you test the sticks independently?
Can you buy another sticks or such to test of the ram are not faulty.

I tested each strip on each slot with memtest86 and there was no mistake.
I put the memory separately and it works very well.