4GB routinely crashes, 2GB doesn't. ???

[hirefrank]

I have a GA-G31-ES2L Rev2 mobo and CORSAIR XMS2 4GB (TWIN2X4096-6400C5DHX) memory. When I install both sticks (4GB) I get a kernel panic after moderate to heavy use. (kernel trap and EXC_BAD_ACCESS errors). Usually it starts with Chrome and Flash crashing and then moments later brings down the entire system.

Believing this was a memory issue, I ran memtest on each stick and in each slot as well as together -- no errors, everything passed. As an aside, when I first installed Snow Leopard, I was only able to install with 2GB of memory -- removing one of the sticks. I was never able to complete the install with a full 4GB of memory.

I have two identical setups (all same components) and nothing I've try seems to work. I now believe this is a tuning issue, either in the BIOS (I am running the latest version, FH) or in the OS.

Does anyone have any ideas?

Thanks,
Frank