Hi!
Just curious, where did you get the new bios?
I flashed a few gpus before and its does have strict procedures. You need to use the exact bios for the particular brand, model and variant. Meaning, you can't use the bios for a 7950 with 2gbs of ram to one with 3gbs or one that is factory overclocked based on my experience.
You can check this out and look for the exact bios version you need
http://www.techpowerup.com/vgabios/Be careful, if you do it wrong, you can brick your card...