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Questions about overclocking the 4850


New Member
Jul 2, 2010
2 (0.00/day)
Hello all,

I got some questions about overclocking the 4850.

My old HIS 4850 ICEQ4 Turbo was getting a bit too slow for my taste, so I started reading about overclocking this card. However, I was dissappointed when I couldn't get past a 700mHz core barrier.

So I started to search for information about bios modding with RBE and ultimately decided to give voltmodding a shot.

I tried the pencil mod found in one of the threads on this forum and managed to get my volts up from 1.058 tot 1.332 volts as shown by my multimeter. When I look into the bios my max voltage is still 1.058. I am wondering whether I actually need to mod the bios after a voltmod or not?

I have searched all the pages on the voltmod threads on both techpowerup and xtremesystems and googled for voltmod tutorials but I still wasn't able to find a good answer. After that I tried to do a bit of trial and error and set the bios voltage on 1.332. I didn't get any problems, though I couldn't overclock anymore. Whenever I tried to rise the clockspeed (tried RivaTuner, AtiTrayTools and AMD GPU Clock Tool), GPU-Z would show me the new clockspeed on the Graphics Card tab, but the Sensor would still give me the old speed even while running games. I've tried GPUTool aswell, but it just resets the sliders to stock speeds when I press apply. When I switch back to stock voltages in the bios, overclocking is possible again.

Now I reflashed to the original bios and started overclocking. I saw some people reaching the 800mHz or higher. Yet my card starts to give artifacts at 740mHz. I do realise that is about 40mHz higher than the first maximum I ran into. It is nowhere close to 800+ though.

So my question is: Am I doing something wrong, or is my card simply not capable of going any higher than the 735mHz?

I hope there is anyone who can help me.

Sep 15, 2009
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In my opinion its not really worth overclocking your card anymore. Just be happy with it until you can get another graphics card. Chances are, you'll probably kill your card in the process of overclocking if it's as 'slow' as you say it is. Cards are not all manufactured the same, some have higher or less capable overclocks. So i guess you have gotten one of the odd ones out, and I think you have done nothing wrong, so it's the card.
Mar 28, 2010
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I needed 1.20v for 740 Mhz and 1.5v for 800+ Mhz on my card.

I don't advise 1.5v+ but up to 1.35-1.40 is safe enough.
Your multimeter shows the voltage being applied to your graphics card's core.

It (pencil mod) lowers resistance in the circuit and bumps voltage up. Your BIOS should still think it's applying 1.058v. Keep it there.


New Member
Jul 2, 2010
2 (0.00/day)
Thanks for the information.

I guess my card just can't push much further, so I will stay at 730mHz and be happy. :)

Thanks for the information about the bios volt vs voltmodding btw. Once again I understand a little bit more!