In what part is my problem? and how can i fix it?

Kareem Ghanameh

Honorable
Feb 13, 2014
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10,640
So guys i hope you can help me out,specs:
core i7-3770k
xfx radeon hd 6770
8gb ddr3 1333
HDD: 500gb,1tb
case: cm storm scout case
psu : 550watts thermaltake tr2 rx
mobo: gigabte z68 xp ud5

Okay the problem started after a while of playing battlefield 4 multiplayer,the game started to crash at random maps/random times,Displaying a black screen and gpu fan suddenly goes to 100% speed,Need to restart so i can use the pc again,okay so this problem keeped happening,I'm sick of it,i took my gpu apart,cleaned it well,replaced thermalpaste,plugged it back in,now i turn on my pc,it displays the bios screen for a sec and then suddenly screen goes black and gpu fan reaches 100% speed,then i tried clearing cmos (removing battery,and putting it back in)
turned on the PC,same sh!t !
but this time only the gpu fan reaches 100% speed,but no bios screen displayed at all.

Notes:
before cleaning the gpu,i had everything working but battlefield 4 not,also i tried a new pci-e to PSU cable,my motherboard got no onboard GPU,i tried to boot without the gpu at all,first time pc rebooted it self after 1 second,2nd time pc booted with no reboot,but i can't see what happened to the screen since there was no gpu,please guys help me,sorry for bad english,and also note that i think the problem might be in the PSU if it wasn't the GPU.