Never ever flash in windows, always in dos
If you have a pci graphics card install it and run your pc from it with thr dead 5770 in the first (top most) pci-e slot...
Lets start at what you need..
* Any Flash drive or USB...
What settings are you using across the board for 4.0Ghz
I've had mine at 4.3Ghz with 215 x 20 (no turbo)
Voltages were 1.350V for CPU and Chipset.
Let it be know that it could complete 3dmark, but it was NOT prime stable