In this in-depth guide we show you how the extract the highest performance from your Geforce 8800 video card, push that GTS past GTX speeds and turn that GTX into an Ultra-beater by following the steps outlined. We evaluate the performance increases along the way by using real world benchmarks; Can a $250 8800 GTS compete with a $500 8800 GTX? Read on to find out.
Overclocking through BIOS mods
Overclocking through BIOS mods
*** Please take note: flashing a modified BIOS to your video card will void your warranty
The VGA BIOS seems to have stored the values of the stock clock speeds. Through this way we hope to alter the 8800's shader clock. With the use of Nibitor we can have a view on what's inside the Geforce 8800 BIOS, here is what you will see once you double-clicked the main executable:
First you must configure Nibitor to read from the right VGA card. To do this, follow those instructions:
A new window will pop-up, select device and press "OK"
Once Nibitor has been configured you can read the VGA ROM by doing the following instructions:
By doing this Nibitor has now full access to the VGA BIOS, this will appear on your screen:
The stock values are being filled in now and we have the possibility to alter the shader clock too. The fastest way to find the maximum shader clock is to edit the shader clock to 1512MHz, as this is still a safe value and once you start overclocking in Windows the GPU ROP domain will not limit the shader domain overclock.
Save your modded BIOS file via "File->Save BIOS...", Nibitor doesn't support flashing VGA cards at this time, therefore we need to use NVFLASH to flash our modded BIOS into the VGA's ROM.
NVFlash Tutorial: Never forget to have a backup bios file available in case flashing the VGA rom went wrong, having a PCI VGA card nearby is not a bad idea either.
Get a floppy disk first. This should be a bootable disk, use the 'format disk' option in Windows to make it bootable. If your motherboard supports booting from USB you can modify your USB stick, this involves a bit more work, but once set is definitely easier than using an old floppy drive.
Copy cwsdpmi.exe and nvFlash.exe (found inside the NVflash zipfile) to this floppy disk/USB drive together with the modded bios file, reboot your computer and make sure that your floppy drive (A)/USB is set as first bootable device. You can change boot order through the mainboard's BIOS. Once your pc has rebooted it will run the boot procedure and start loading a small DOS version which is needed to use NVflash. Once DOS has been successfully loaded the command prompt shows up:
If you're not on the A disk, type in "a:", without the " " off course. Now, to flash your VGA card, type the following: nvflash -5 -6 xxxx.rom (where you replace xxxx with the name you gave to your modded bios file), and hit ENTER.
NVFLASH will now run through some security checks and will then flash your card. Once the BIOS flash has been done you will need to reboot your pc. That's it; you have made a successful bios mod.
Once you've found the maximum stable shader clock you will have to re-edit your BIOS for optimal performance. Every highest clockspeed you obtained should be edited into the bios. If you're still not 100% sure of your overclock, or if you only use your highest clocks for short benchmarking session, you can use the following tool to calculate which shader clock should be programmed in the BIOS.
Do note: this piece of code gives you an idea on how the shader will scale up when the GPU speed is increased, please note that for some GPU speeds the shader clock speed shown is not entirely correct;
Read on where we will find out where all this modding has brought us so far ->