Ok so heres how to OC the cards...
Disclaimer: This is only recommended for Advanced users. This may and/or can cause serious damage to your video card. I am not responsible for any damage that may occur from uses of this guide. This may also void you warranty. I.E. If you fry your card don't blame me you have been warned
Thing you will need:
NiBotTor 2.8a (or newer)
http://www.mvktech.net/index.php?opt...filecatid=1591
Coolbits 2.0
http://downloads.guru3d.com/download...t=815#download
Nvflash ver. 5.31
http://www.mvktech.net/component/opt...rent,category/
bootable Memory key/Floppy disk/ Bootable CD
Step 1: Coolbits
1 Install cool bits
2 Go to the Display propertes, settings,GeForce 7900 xxx tab
3 Click on "Control Panel User Interface"
4 Click on "Classic Nividia Control Panel", Click "Apply"
5 From the Menu on the Left Select " Clock Frequency Settings"
6 Click on "Manual overclocking", Click "i accept" on the license agreement
7 Click on "Detect Optimal Frequencies", it will test the for optimal clock (the screen may flicker or blank for a second"
Once the test is done it will show what it considers the Optimal clocks for your card are. Write these numbers down these are the starting clocks speeds.
Step 2: NiBiTor
1 Extract NiBiTor to you system and Lanch it
2 Select 'Tools" from the menu
3 Select "Read BIOS", then click on "Select Device"
It will display : Deviceid: 0xxx (unknown), Click "OK"
4 Select 'Tools" from the menu
5 Select "Read BIOS", then click on "Read into NiBitor"
Click on "OK" on the Device unknown pop-up, Note: "Geforce7 series" will be listed in the drop down above the OK/Abort buttons.
6 Click on "File" then selecst "Save BIOS", call it default (This is to make sure you have a backup of the default bios in case of emergency. I recommend saving it to same folder you extracted NiBitor to, so it easy to find)
Ok now you have the vbios loaded in to NiBiTor, on the "Clockrates" tab you will see the 3D clocks. Now it time to edit the clocks.
7 Click in the box next 3D under core and enter the core clock you found in step 1.
8 Click in the box next 3D under memory and enter the memory clocks you found in step 1.
9 Click on "File" then selecst "Save BIOS" save it using any name you like (I recommend saving it to same folder you extracted NiBitor to, so it easy to find)
Step 3: Flashing the card.
1 Move the nvflash files and the edited vBIOS to you bootable media
2 Reboot the system using your bootable media
3 Once at the Dos prompted type "nvflash xxxxx.rom" (without the quotes. xxxxx= what you named the file)
Nvflash will load, then display some card info and display the message "Update display adapter firmware? Press 'y' to confirm (any other key to abort):"
4 Press "Y" to flash the bois.
Contgrats you have now flashed your video card and its time to test your changes. I would recommend running a game or 3dmark looped for 15 to 20 mins to see if the card is stable before re-editing the bios to up the clocks further.
Note: If you see corruption in the graphics, or lock-up you will want to lower the clocks you have gone to far..

Sorry for any typo's
Enjoy
Zyb