Overclocking is fun! It’s nice to be able to get out of your “lower end” gfx card the same performance as another, double the price, “better” card. And, since we’re talking about ATI cards, it can be profitable too, if you’re mining BitCoins 
My new toy is a Sapphire Radeon HD 5830 Xtreme video card – cheap and fast. Not being a gamer, I think you can figure out what I do with it. And since I needed to get the most performance out of it, overclocking was the logical step.
By default, my card would run at 800 MHz in full-load. I could use aticontrol or AMDOverdriverCtl in Linux to push the card to 900 MHz, but I wanted more. After a little digging around on the Internet, I found out that overclocking is not only possible, but also fairly simple. So here goes:
Requirements.
- a fairly recent Radeon. This post is about the 5830, but the steps are generic enough so they should work with other chips.
- overclocking software. I use aticontrol and AMDOverdriveCtl on Linux.
- Radeon BIOS Editor. As the name says, this is a tool that will edit the BIOS of the card. We will use it to increase the upper frequency limit to more than 900 MHz.
- ATIFlash. This is a DOS-based tool that can dump and write ATI BIOSes to the card. The cool thing about it is that even if the card is “dead” (doesn’t do POST), it can still push a working BIOS to it and make it work again.
- a DOS boot disk for the BIOS update. You should write the DOS image to a USB stick with at least 5 MB of free space. The image in my post has more than enough, just use that.
- good understanding of the fact that your warranty will be void and I will not care if you fry your card, kill your cat, breakup with your girlfriend or make millions mining BitCoins. You are warned.
Step 1. Copy atiflash.exe to the DOS boot disk.
Step 2. Boot your computer from the DOS boot disk, after booting is complete you should see the following prompt:
C:>
(oh this brings back memories…)
Step 3. Find out the ID of the card you want to overclock:
C:> atiflash -i
You will see a list with the video cards on the system. If you have more than one card, make sure you get the correct one. On all the next steps, I will assume there is only one card, with ID 0. If your ID is not 0, use the correct ID in all the following examples.
Step 4. Dump the card’s BIOS.
C:> atiflash -s 0 bios5830.rom
After this step you will have the original bios of the card in the file bios5830.rom. Backup it! If things go wrong, it will be the only thing that can resurrect your card.
Step 5. Reboot the computer to your usual operating system and launch Radeon BIOS Editor. It’s a Windows program, but it runs very well with Wine on Linux (that’s how I used it).
Step 6. Load bios5830.rom and check that it loads ok. You should see information about your card, make sure they look correct. Then switch to the “Additional features” tab.
Step 7. In the “Increase overdrive limit” box, choose “Method 2 – No hash” and move the “Upper limit GPU” slider to a larger value. I set it to 1100 MHz. Don’t touch anything else!
Step 8. Save the BIOS file and exit RBE. Use “Save as…” and don’t overwrite the original file!
Step 9. Copy the modified BIOS file to the same DOS disk you used before. Don’t overwrite the original BIOS file! Remember what I told you about backups!
Step 10. Reboot the computer using the DOS disk.
Step 11. Write the modified BIOS image to the card (same ID as before!):
C:> atiflash -p 0 modbios.rom
If, after this step, you get an error, your card is locked and you need to unlock it. Don’t worry, it’s as easy as running:
C:> atiflash -unlockrom 0
Then re-run the write command above.
Step 12. You should now reboot the computer and run the overclocking software. You should see the new upper limit at 1100 MHz instead of 900, and you should be able to set the GPU frequency to more than 900 MHz without any problem or error.
For example, using additional cooling (large 10k RPM fan) and no computer case I got my card stable at 1040 MHz and 62 degrees Celsius. Not bad at all! Its overclocked performance is the same as the stock performance of cards who cost exactly twice here in Romania.
So, overclocking FTW 
. Enjoy!
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