GTX 260 Balck-Out Issue I Need HELP!!!

ts more like RE-Posting because i got no answers in the previous one.
I have GTX 260 216 core SC this is the full model name " EVGA 896-P3-1267-AR GeForce GTX260 Core 216 SC Edition 896MB DDR3 PCI-Express 2.0 ".
my problem was that my video card blackout when it is on stress approx. 5mins and i havnt over clocked it or anything and it used to be fine before, been using it for 5 months but in the last two months i havnt been able to play any games tryin to figure out why does it black out i have changed my power supply with another one and still the same problem so with latest drivers and reinstalling OS except for Windows 7 RC1 build 7100 it was running smoothly but windows 7 has some conflicts with my work programs so i cant use it either.
but when i bought it the first time i changed fan speed in Bios config so it would run on 63% IDLE, so i was told that might be problem that when i did that i might changed something that caused this problem.
so could anyone please lead me to download bios source even if theres any updates it might help and how do i flash it.

also i checked forums for flashing Bios i followed everything and when i type flashing command instead of confirmation message i get this error " Unable to map device address space" .

i've posted the same post on evga Fourms there were many hits on the my post but no answers, and i was told to contact Support and when i did all they told me was they directed my request to someone else so i ship it back to United States which will cost me almost Card Price..

Please HELP me!!

Sorry for the Long post.

Thanks in Advance..

Sorry for English Posting but i have problem with Arabic Typing.. i Apologize about that

Have u checked ur Temp. at load ?
and try using another PSU and see if the issue still persists

the problem is im the only one i know with PSU 500w+ and im not sure if its really the problem since i changed it with new one but the same brand.
also about the temp its not the problem because as i mentioned up there i edited fan speed so max temp i get in stress is 65~73c
and when i was told the problem might be Bios Editing that i did before i tried flash it with original source and it gave me that error " unable to map device address space" so is there anyone familiar with that error? or it was me doin something wrong with the command.
Thanks

Do you have the original BIOS Backup ?

If so, you can check the command to "Force" flashing the BIOS

Hi
Do u have a warranty؟
If u do, u may call EVGA and do the RMA they will give u a new one I mean new card.

sorry I don't have experience with Nvidia cards :) I'd like to help, but sorry

best wishes to u

i had backup of the original one but i lost it, but i got another one from powertech configured to SSC i think which i tried to flash but that error which im not familiar with or any others happened. so if you know any solution for that error or any other ways to flash it that would be very helpful, also about warrenty thing that will cost me like half to same card price to ship it back to U.S since it weight about 1.6kg.
i posted the same problem on powertech and i was told its my PSU after they saw image of PSU performance,
https://img194.imageshack.us/img194/3248/asusspecs.jpg
so they told me to downclock the card as much as i could with evga precision and try to do the same stress to see if it goin to blackout again so it would be card problem or run smoothly due to less stress on PSU which means its PSU problem.
and the result was running smoothly with the card downclocked, so i guess i have to buy new one after all and sell that one.
but still i have to make sure but i cant find anyone to test the card on another computer.
also i need help with flashing the card since the current bios running right now isnt the same size as the original one.
Thanks.