HD 4870 X2 mobility votage increase.

Sorry to keep making new topics, but I was hoping someone could point me in the right direction of a tutorial or directions on how to up the voltage going to my 4870's. They are running ice cold, and I can't get them stable past 635mhz without upping the voltage - and I haven't been able to figure out how.

 

For my 5870CF its in the bios. Right under CPU voltage.

 

The only things in the bios I can change are the cpu voltage and the ram voltage.

 

Heres a link to a tutorial on how to flash your cards (the procedure is the same no matter if it's 4870's or 5870's)... that's the only way to increase the voltage. This will increase the heat produced by a fair bit and you could brick your cards if it's done wrong or if something gets corrupted during the procedure.

Many have done it without incident including me... just make sure you're careful and are aware of the risks.

http://forum.notebookreview.com/alienware-m15x/474717-m15x-ati-5870-mod-174.html


EDIT: note that where it says "5. At the Command Prompt, type in "atiflash -p 0 5870m.rom" you will also need to flash the second card by typing this in a second time and adding a 1 in the right place so it will read "atiflash -p 1 5870m.rom".
Also for all the places it says 5870 just change it to 4870.

EDIT 2: you can also get the vbios from your cards by using the vbios dump feature in gpuz. I found this quicker and easier than doing the command prompt thing.

 

you have to flash the bios. The ty part is that you can only bump them up another .05v, they're still completely voltage limited. Mine run at 650 and furmark doesnt even get them over 75c. Wish there was a way to get them higher, I have no doubt that these things could be clocked well over 700mhz.

 

There are two risks. Loss of power during the flash, and flashing a corrupt VBIOS onto the card. Make sure the laptop is plugged in and the battery is installed. Before you EVER flash anything, use the command "atiflash -cf ____.rom" for both the old VBIOS and the one you're about to flash. If the checksum is not exactly the same, don't flash it.

 

Where would you type this command?

 

When you're booted from your USB stick before you input 'atiflash -p 0 _____.rom'.

 

Thanks for all the info. I'm going to try it now - I'll let you all know how it goes.

 

I was able to get both gpu's at 1.150v. However, the highest stable OC I can still manage is 635mhz core 950mhz mem. 650mhz is stable in a handful of games, but not all.

Card are still running nice and cool. 75C max. Anybody have any tips on getting the clock rates higher?

 

At this point I'd say you've just reached the natural limit of the cards. Try turning crossfire off and seeing if the primary card can go a bit farther, or over clocking the secondary card higher than the primary. Make sure you're looking at all 8 thermal probes in gpu-z and manually selecting both cards in the drop down menu. They can't all be 20% monsters.