Computer randomly freezes

I built this PC about 3 weeks ago. I ran Memtest once and it passed. Now my computer locks up/freezes randomly. Three days ago, it froze after 3 hours of play. Yesterday it didnt freeze once, which i played for about 8 hours. Today after 10 hours it froze.
Anyone know what could be the problem?
Answer #1
Any Of This Info Help For You??
http://pirules.com/computer_freezes.aspx
Answer #2
what is your operating system…maybe smthg need update..it happend to me once with a new pc i bought and i installed windows xp sp2 and i got freeze problem and i could fix it by updating to SP3 ..
another option is heating..try to open the cover of ur pc and keep working and see what happen
Answer #3
All my temperatures seem to be normal, and also I went to x64, in which previously i had freezes in x86 edition.
Answer #4
i got same problem as also, untill now i still looking for answer…
Answer #5
what are you spec it might a hardware problem you did say that you hand build the pc so it might be incompatible hardware to motherboard
Answer #6
I dont want to jynx myself but i think i fixed the problem.
My 790i motherboard was reading the ram with 1.5 volts(or w.e electric currency), when the ram was specified for 1.625v on newegg. I went on bios and changed it. Its 13 hours on and still no freeze. Hope its fixed!