OCZ Titanium Aplha Passes memtest then fails.

I overclocked my e6600 to 3.2(8*400) with a ds3 motherboard with f10 bios, the multi is at 2.5 so my ram is at 1000 its rated speed my timings were manually set to 4-4-4-15 its default i then ran memtest for 11 hours it said 36 passes with no errors then a few days later my computer randomly crashes i then run memtest once again now it fails within a few min of it running. This ram has already been rma'd is this a motherboard failure or a ram failure? Should i return the ram for something else or should i stick with this failure ram? Can someone please help.

I'm puzzled by this - doesn't "been rma'd" mean that you've already sent the RAM back, and thus are waiting for the replacement?

Actually, RMA = Return Merchandise Authorization (or slight variant).
My original question remains open: if "this" specific RAM module has already been returned, it would seem to be too late to decide what to do with it...