Sapphire HD4870 1GB Shipped with wrong bios?

I got this card and it is working fine until I tried to play an MPEG files or any video file which need hardware acceleation using AVIVO / PowerDVD codecs and suddenly once I click on any video file, my screen flickers, I noticed that the card downclock itself to 500/500 each time I click on the movie or when I play it which is strange as all the 4870 has a fixed memory speed so I edited the bios with RBE setting 900 memory speed on all clocks and now no more flickers, it is really strange as my mate has same card as mine and all his clocks on the memory clocks are 900.

this is how it looks on my original bios:
http://img227.imageshack.us/img227/3687/4870up9.jpg

I edited them to this new clocks, I copied them from my friend HD4870 1GB:
http://img76.imageshack.us/img76/1370/new4870mt7.jpg

This is the original bios saved with GPU-Z if someone want to check it:
http://rapidshare.com/files/164051076/RV770.bin.html

Yep same thing is happening to me man. I set them to be 871 / 950. Flicker still occurs for me ofcourse because I set my memory higher then what it is by default. Duh,,, I can prob fix this issue easy by just making all my memory settings 950. Duh.... I will go do this now because the flicker is irratating as hell.