Let me get some background out of the way.
I built this computer 2 months ago as my first build.
Specs:
Intel Core i5 3570k (not overclocked yet)
Asrock z77 extreme4
Evga geforce gtx 670 ftw
8GB (2x4GB) Corsair XMS3 DDR3-1600
So for the first month everything went well. After that I got a blue screen I thought nothing of it at first it happens occasionally. Well it got more and more frequent to the point it was happening at least once a day (generally when I'm playing Smite). I decide to run a memtest with all my RAM still installed. Within a minute I have 140 errors all saying the same thing "cannot write to memory". Well I remove one stick of RAM and then the computer wont even turn on. The case fans come on but no reaction from the monitor, mouse, or keyboard. I shutdown the computer and removed the one stick I had in the computer and replaced it with the stick I had previously taken out. Over night I ran the memtest and did not get a single error in the time it was running (about 8 hours).
1. Is it safe to assume the first RAM stick was the issue?
2.Does Corsair have a warranty for their XMS3 RAM?
3. If I buy more another 8GB (2x4GB) kit can I use it and the one good stick I have even though my motherboard calls for duel channel? (so three sticks of RAM in a duel channel mobo)
4. Does the new RAM have to be the same? (Do I need to buy XMS3 or could I buy Corsair Vengeance so long as it is still DDR3-1600 and use it with the one good stick of XMS3 I have)