This is how i done
1 Download Winflash
http://www.techpowerup.com/bios/bios/winflash105.zip and save your bios to a file
gtomod.bin
2.) Download HXD Hex editor from here
http://mh-nexus.de/HxD.htm#whatsnew
3.) At line 00000070 find the key "19". Change it to "18"
4.) Save As> "
gtomod.bin "
5.) Open gtomod.bin with RaBiT2.0a found at
http://www.techpowerup.com/downloads/283
*You will get an error "Bad bios?" > Click yes and continue working on it
6.) Save As >
gtomod.bin > Yes to replace
7) Make a bootable floppy disk , in My computer right click on floppy A: >format> and select Create an MS-DOS-stratup disk>OK.
8) Get atiflash 3.09 and put both files on a floppy I put this files and files described below on a USB flash for sefty only used the floppy for booting than typed c:\ to use the files from USB flash
9) Next download sapphire xl bios from techpowerup.com
http://www.techpowerup.com/bios/Sapphire.X1800XL.256.Samsung14_050923.bin
and throw that on the floppy as well or USB flash, i changed the name of my bios to a short name so it works easy in dos such as
sapxl.bin
10) If yours does not unlock to 16 then you can just use your default
gtomod.bin bios for this step.
11) Anyway copy that bios to your floppy as well, i named mine
gtomod.bin
12) And last thing you can make a flash.bat file by just making a new text document and inserting the lines exactly as shown here
atiflash -newbios -f -p 0 sapxl.bin
atiflash -f -p 0 gtomod.bin
13) After you put those 2 lines in the text file, save it and then rename it to
flash.bat and of course throw that onto the floppy as well or USB flash
14) You should now have 5 different files on the floppy or USB flash, 2 bios's, 2 files from ati flash 3.09 and also the flash.bat file.
Final : That's it now you can go boot to dos and run the flash.bat file and if all goes well you should have a x1800Gto thats able to change all voltages and show temps in AtiTool
and with 16 pipes activated if you have a lucky card.