865PE NEO2 PFISR won't boot

Recently I upgraded a few items on my PC which has been running fine for 18 months or so. I changed out the video card and bought double the memory of the same brand and type it had in it. I went from 1gig (2 sticks) of Corsair Value Select and added two more sticks of the same type. But now it won't boot. The power is on but no output whatsoever.

I RMA'd the memory thinking that might be the problem but it's the same with the new set. I tried all sorts of memory/slot combos. Basically, the new memory works fine if you swap it out with the old memory in bank A on the mobo. That's how it's running right now, so I know all of the sticks are good. I can take a third and put it in either slot bank B and it'll boot, but obviously not run properly. But any combination of these four sticks and the system won't boot!

Do you know of any compatibility issues between this mobo and memory?

I'm running this system:

Win XP (SP1 I believe)

865PE NEO2 PFISR

P4/3.0CGHz, 800M 478P/512K HT

DDR Corsair 512MB X4 (400) running 2.7v

Dual 80gb samsung HDs running SATA

Sapphire X800GTO 256M video card

Antec Sonata case

TruePower 380Watt ATX12V

Thanks for the reply. I'll try booting with memtest, but will I even get that far if I can't get it to post with four sticks?

I was wondering if the PS might be a little low. At this point I'm thinking of just RMA'ing the new memory and skipping the whole attempt. I may just order two 1gig sticks of Corsair that the website says are compatible :sigh!: