GeForce 2 GTS BIOS modding

After a couple of hours trying to mod my system bios with no success, I gave it up. I rebooted and saw the boring GeForce 2 GTS BIOS display as usual. While the machine booted, I got a whole new idea. What about GeForce BIOS tweaking?

At first I didn't believe that it was more popular than system bios modding, and that I wouldn't find much, but I wanted to try anyway. I started IE and searched with AltaVista. After a while I found a lot more information than expected. I found several howtos, forums on the issue and apps I needed.

WARNING! We do not take any responsibility for this. It worked ok for us; it may not work for you. Don't forget that you can always post you questions/ideas in our forums.

Overclocking

I found out that I could mod my BIOS with new core and memory speeds. In that way I never more needed to load all those overclocking apps on start-up or install everything again after every format. I only needed to do it once and it went painless.

This is what you need:

• Reference BIOS and the script for GeForce 2 GTS without flat panel and TV-out ONLY!
• Biosmod and biosmoddll
• NVFlash and TSR VGA-BIOS tool

Howto

1. Open the script file in a txteditor
2. Search for "Struct bmp_MemInitTbl"
3. Change
   word ? // XXXMhz (*100) (ie: 166Mhz = 16600)
   word ? // XXXMhz (*100)
   into
   word memoryclock*100 // XXXMhz (*100) (ie: 166Mhz = 16600)
   word coreclock*100 // XXXMhz (*100) Be careful with "// Strap 1111 - Memory Type 15" you have to do the memoryclock*200 instead of *100
4. If you have SDR memory then change
   word ? // 0 = SDR, 1 = DDR
   into
   word 0x00 // 0 = SDR, 1 = DDR
5. If you have DDR memory then change
   word ? // 0 = SDR, 1 = DDR
   into
   word 0x01 // 0 = SDR, 1 = DDR
6. Save the file, either go on to "Changing default message" or to "Flashing"

Changing default message

I found out the default message could also be changed. That is really a goodie! ;)

1. Open the script file in a txteditor
2. Search for "Struct SignonString at @SignonMsg". The default script-action is "byte ?"
3. Change the ? to 'Whatever you want the BIOS to say'. Don't forget the quotes!
4. Count how many characters your message is.
5. Convert it from decimal (DEC) to hexadecimals (HEX) by using this table.
6. Search the file for // Signon Message Length. The default is "word ?"
7. Change the ? with the HEX number you got including 0x.
8. Save the file and goto "Flashing".

Enable/Disable SBA (Sideband transfers)

I've heard that disabling the SBA will result in a 5-7% performance decrease, but a OC system becomes much more stable with SBA disabled.

1. Open the script file in a txteditor.
2. Search for "// INIT_NV_REG NV_PEXTDEV_BOOT_0 (Do Not Modify)".
3. Change
   dword 0xFFFFF7FF // AND Mask
   into
   dword 0xFFFFF3FF // AND Mask
   to enable SBA.
4. Save.

Flashing

This is the scary part! :) If anything goes wrong then your Geforce 2 GTS may work incorrectly or not at all! Therefore, read everything on this page carefully, make sure you've understood everything. You may ask for help in our forums.

1. Start your Biosmod app.
2. File -> Open -> smg2gts.rom
3. Script -> Process script -> Browse to the scriptfile you've edited. Then after a sec or two you get up a new window. If it doesn’t display any warning or error messages, choose save as and save it as smg2gts_new.rom. If you get errors, then you haven't edited the script right, try again.
4. Unzip NVflash, dos4gw, TSR-BIOS tool and your "smg2gts_new.rom" to C:\temp
5. Boot into DOS-mode. You may have to use a Win9x bootdisk.
6. First try to flash with the TSR-Bios tool to see if everything is ok. If it is, then reboot and flash your bios with the NVFlash.

Good luck! :)

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