Display sometimes freezes to a single color black screen

[iTree]

i got a new XFX HD 6750 1GB and i ran vision center auto clock and it decided set my card to 860mhz and memory 1210, the card i ran at 99% for a bit and it reached 52C tops so i played games for 2 days but now its been getting kinda frequent times where it will randomly freeze to a black screen of a color usually of the main color of whats full screen at that time, i haven't had it freeze while system was idle on desktop not rely sure what is making this happen, also i looked up and saw people saying this card can reach 860 fine and i seen people say even above 1300 on the mem, so idk, what might be the issue ?
for the mean while i have lowered the clocks to 840 / 1200(790/1100 now), seeing if i run into a lock again

also these are my other hardware parts

rosewill green80 630w
biostar TA880GB+ (PCIe x16 2.0 slot)
4GB ram speed to 1466
athlon2 450 rana clock to 3.52x2

also my mother board bus speed is set from 200mhz to 220mhz

 

[iTree]

You need to reset the gpu clocks back to default, as the overclock is not stable.
Also put your motherboard bus back to 200 and do further tests to see if the problem is alleiviated.
What is your psu?

i wrote the wrong psu in the original post
its a Rosewill Green Series RG530-S12 530W
heres a link to it on newegg's site
http://www.newegg.com/Product/Product.aspx?Item=N82E16817182199

also just a wonder why might mine not be stable at a lower overclock then i see other people put on theirs ?

 

[iTree]

i set things back and put the card to 800 / 1150 and im still getting the blank screen issues, it does fine for a while when i lower it and then blanks out again, i also cant normal shut down only manual shut down when this happens ,, now at 790/1100

 

[iTree]

im starting to think my card maybe a bad card or something,, at 790 / 1100 its still getting issues

this is a picture of whats it showing now

for the mean while i set it back to all default whats 700/1000 whats disappointing