How to Over-Clock Your ATI 4870s
First the disclaimer: I'm not responsible for you bricking your cards. If you are uncomfortable with flashing the BIOS do not bother with this. If you do something wrong and can no longer boot your system I cannot help you and your Dell warranty will be at risk. BE CAREFUL AND EXTRA PARANOID!
Now that part is out of the way there are different ways to over-clock your GPU, here is a quick step by step on how I do it. When doing these steps turn off any CPU over-clocking you may be using.
Tools needed:
A bootable USB stick
ATIFlash
RBE (Raedon BIOS Editor)
GPU-Z
1)
Get a copy of your current BIOS and make an additional copy of it and store it somewhere besides your M17x. Do this by placing a copy of atiflash on your boot stick. Turn your M17x on and get into the system BIOS. You need to change the boot order of your system to look at the usb stick first. Then save, exit and boot off the stick. At the command prompt type
atiflash -i. When you do this it should report back to you information on your 4870. It will show two cards if you have a crossfire setup. If you notice the cards are EXACTLY the same (I would assume somewhere written in the bios that one card is defined as Master and the other as Slave). Out of paranoia I treat them as two different cards and repeat the steps twice. Now to get a copy of the bios type
atiflash -s 0 bios0.rom. This will take a copy of the bios on card 0 and call it bios0.rom. Repeat for the second card,
atiflash -s 1 bios1.rom. Like I said before keep an additional copy of the bios files in a separate location. If you want to go back to stock eventually it's best to load the original copies.
2)
Use RBE to change the clocks in the bios files. I normally just take my copy of the bios and drag and drop them right on RBE in Windows Explorer. That will open up RBE with the BIOS file loaded. You'll get a warning about the GPU not having ATI overdrive capabilities. Click OK to it. Click on the button on top called Clock Settings. Here is where you'll set your different clocks and voltage to save to the bios file. There is also a little wizard button you can use that will simply ask you how you want the over-clock settings to look like and your under-clock settings. You can use this wizard if you are a beginner. Once you change your clock and/or voltage settings save your bios. In this example I will call it nbios0.rom for card 0 and nbios1.rom for card 1. Put a copy of these two new files on your boot stick.
3)
Flash your cards with the new settings. Reboot your system and boot off the usb stick once again. Here is another step to do out of paranoia. Verify that the checksum for your original bios file and new bios file are exactly the same. If they are not it has become corrupted somewhere along the process. Type
atiflash -cf bios0.rom (this is the original file) then
atiflash -cf nbios0.rom (this is the new file). The output should be exactly the same. Do it also for card 1. Once you are comfortable everything is OK flash the new bios by typing
atiflash -p 0 nbios0.rom. It will tell you it's successful (hopefully) and to reboot your system but DO NOT reboot if you have a second card. Repeat the process,
atiflash -p 1 nbios1.rom. Once that is successful pull your usb stick out and reboot. Once you're back into Windows use GPU-z to verify your clock settings.
Problems? See this thread at archive.org.
