I have strange RAM problems too.
I had originally 4gig of DDR3 128x8 PC1333 2G AUM 2809 whatever that means.
The computer wouldn't start at all with the 2 modules in. The fans turned and then stopped and started again with the MOBO lights coming on and off. This repeated ad infinitum, no boot up screen.
I removed one module and it started up OK.
Either module alone, worked fine.
I bought 2 more to give me 8 gig, put them in and .... it wouldn't start, same again.
I put 2 modules in and lo and behold... it started, 3 modules... OK.... all 4 modules and away it went... for 2 weeks and then Windows 7 wouldn't start and kept trying to repair itself... which it couldn't.
I removed the ram, leaving only one module in and it all worked fine again, 2 gig of ram, one module.
I bought a Corsair XMS3 6gb pack and no way will the computer start with any combination of the 3 modules, not even one on its own.
It will only work with one( any one ) of the original 2 gb modules.
I am now bald from having torn out my hair and at a complete loss as to what to do next.
Anyone help ?