hey, i've got this problem where my computer crashes this is my story

i bought a new computer last month and built it myself, it worked fine untill i bought a new cpu fan which is this one
Canada Computers - Cooling > CPU Cooling : Thermaltake CL-P0466 CPU Cooler for Intel Socket 1366/1156/775 & AMD 64 754/939 & AM2+.

at the same time i installed this fan i also installed a 120mm one... which didn't have enough room to fit so i just pushed it in there as hard as i could... thats when the crashing began.
i cut the 120mm fan so that it would fit in my computer without putting any pressure on my cpu fan, but the crashes continued..

i took out the cpu and found there was too much thermal paste on it. (my stupidity),, so i got both the motherboard and the cpu RMA
after i got both new parts the crashes were less frequent but still occurred. also the computer is running much slower then it was when i first got it, which was before i got the new cpu fan and when everything was running fine with no crashes...

i even tried changing back to stock cpu fan and the crashes continued..
i know its not the motherboard for sure and that its not the cpu cause i already got new ones from RMA

the crashes don't show any blue screen, the computer just freezes where it is without rebooting or anything.. and my sound just keeps repeating the same sound when it stalls.

it stalls whenever it wants to, but sometimes if i really want to try to make it stall i must download torrents, install 2 games at once, and open like 30 websites, thats when it crashes for sure. i know its not my windows or software, cause i installed windows 32x and 64x with vista and windows 7 and i still get the crashes.

i can't find anything wrong with my cpu.. but i was looking up psu voltage recently and my readings from speedfan were kinda weird... i need to know if this is normal

my vcore1 is 0.88V
vcore2 = 1.57v
+3.3v = 3.36v
+5v = 5.08
this is where its kinda weird, not sure if this is normal
+12v = 1.27v ( this one keeps going up and down wildly)
-12v = -0.92v
-5v = -8.67v
+5v = 3.63v
vbat= 3.14v

this is my computer specs

i got a i5
motherboard p55m-ud2 gigabyte
corsair 750w
i have 8 gig of ram 1333 mhz 2x2gb kit patriot dual channel kit two of those...
2x sata lg dvd rw
nvidia gtx 260 geforce
antec 900 case and i added 2 extra 120mm fans as well
seagate 1tb 7200.12
cpu fan is a Canada Computers - Cooling > CPU Cooling : Thermaltake CL-P0466 CPU Cooler for Intel Socket 1366/1156/775 & AMD 64 754/939 & AM2+.

and i also have two extra 120mm fans installed inside.