HD 4850 Overclocking

[octopus41092]

Ok, so I'm using ATI Overdrive to overclock my HD4850. Currently, I have an Accelero S1 on it with a 120mm fan attached to it that does about 140CFM.

Now, the temps are fine, especially compared to the temps with the original stock cooler. The problem is that I can't even push the GPU to past 680MHz otherwise it'll start showing artifacts in ATITool. But, another thing thats even worse is that I can't even finish a run of 3DMark06 unless it's at about 670MHz. The temps don't go over 55C, which was what it was idling at on the stock cooler at 100%. So, would increasing voltage help to allow me increase the clocks even further? If so, how would I do that?

Next, my memory won't overclock over maybe 1050MHz otherwise it'll show artifacts so also would increasing voltage help there t?oo? One thing I'm worried about though is the temps on the memory because it doesn't show it in ATI Overdrive, so is there a way to monitor the memory temps?

Also, I heard that all the Accelero S1's after May are having the new voltage controller heatsinks. I'm not sure if that's really needed as they said it wasn't and it seems to function fine without it. However, would those help me to overclock even further or are they unnecessary?

 

[runawayprisoner]

1) Use autotune, and let autotune find the best settings for your card first, then if it is close to 700MHz (core), you are in luck. Stop the test, then push to 700MHz, and you are good to go. The technical details behind this are really lengthy, and it falls into a completely different kind of discussion, or I don't want to make it too long for you to read.

2) Increasing memory clock helps very little. Pretty much if you can get it to about 1050Mhz or 1100MHz, then you'd better just stay there.

3) voltage controller heatsinks will be an incredible help! Believe me or not, those voltage regulators are going to be more of a problem than all of the other components, once you reach higher clocks. They are the reason why some people just can't get higher clocks no matter how high in volts they go. Truth be told, the voltage regulators overheats extremely easy. If you are not careful, they can reach 100C and beyond before you can even say ahh... When they overheat, the card will just come to a complete stop, and then your computer will reboot, and the cycle will repeat for as long as they keep overheating. What's even more annoying... is that once they have overheated once, they will continue to do so for a loooonnnnggggg time.

From my own personal experience, I find that I only need to blow some 100CFM fan directly at the voltage regulators (and the capacitors around them) to reach higher overclocks. But be advised: cool the regulators if you plan to overclock anywhere past stock! And I mean... anywhere at all! Be extra cautious, otherwise you are going to end up with a card that overheats on an hourly basis! Only fix so far is to let it cool down for a while, it seems.

 

[octopus41092]

Originally posted by: runawayprisoner
1) Use autotune, and let autotune find the best settings for your card first, then if it is close to 700MHz (core), you are in luck. Stop the test, then push to 700MHz, and you are good to go. The technical details behind this are really lengthy, and it falls into a completely different kind of discussion, or I don't want to make it too long for you to read.

2) Increasing memory clock helps very little. Pretty much if you can get it to about 1050Mhz or 1100MHz, then you'd better just stay there.

3) voltage controller heatsinks will be an incredible help! Believe me or not, those voltage regulators are going to be more of a problem than all of the other components, once you reach higher clocks. They are the reason why some people just can't get higher clocks no matter how high in volts they go. Truth be told, the voltage regulators overheats extremely easy. If you are not careful, they can reach 100C and beyond before you can even say ahh... When they overheat, the card will just come to a complete stop, and then your computer will reboot, and the cycle will repeat for as long as they keep overheating. What's even more annoying... is that once they have overheated once, they will continue to do so for a loooonnnnggggg time.

From my own personal experience, I find that I only need to blow some 100CFM fan directly at the voltage regulators (and the capacitors around them) to reach higher overclocks. But be advised: cool the regulators if you plan to overclock anywhere past stock! And I mean... anywhere at all! Be extra cautious, otherwise you are going to end up with a card that overheats on an hourly basis! Only fix so far is to let it cool down for a while, it seems.

Using auto tune I get up to 700MHz no problem. But my problem is that its unstable. Given what youve said about the voltage regulator heatsinks I think that might be the problem. Now I'm pissed at Arctic Cooling for saying theyre not needed. But anyways do you know if there are any heatsinks I could get for the voltage regulators on the HD4850 from newegg?

 

[error8]

Voltage regulators are made to work at temperatures in excess of 100 C, low voltage of the gpu and video memory is the culprit for low overclocks. And never use autotune, since that program is unable to find a stable overclock. It will just increase your clocks without really testing them.

Arctic cooling is right about the "no need for heatsinks on the voltage regulators", since those will be COOLER with the S1 and the 120mm fan, then they would have been with the stock cooler. The stock cooler has the bad habit of trying to cool everything on the card, but in this process it will transfer a part of the heat generated by the gpu (the hottest thing on the card) to other components that tend to be cooler, like the memory and voltage regulators. So when you're using something like a S1 cooler, the heat from the gpu is transferred "isolated" to the ambient air without heating up anything else during this process. Of course , heatsinks on the power circuit will not going to do any harm, but it's not going to improve your overclock. They can be helpful when you are really stretching the card limits with very high voltages.

EDIT: ATI 4850/4870 volt mods can be found here http://www.xtremesystems.org/f...ad.php?t=190990&page=3

The easiest and maybe the "safest" vmod is the pencil one, since it can be erased and it won't leave any scars on the card.

 

[octopus41092]

Originally posted by: error8
Voltage regulators are made to work at temperatures in excess of 100 C, low voltage of the gpu and video memory is the culprit for low overclocks. And never use autotune, since that program is unable to find a stable overclock. It will just increase your clocks without really testing them.

Arctic cooling is right about the "no need for heatsinks on the voltage regulators", since those will be COOLER with the S1 and the 120mm fan, then they would have been with the stock cooler. The stock cooler has the bad habit of trying to cool everything on the card, but in this process it will transfer a part of the heat generated by the gpu (the hottest thing on the card) to other components that tend to be cooler, like the memory and voltage regulators. So when you're using something like a S1 cooler, the heat from the gpu is transferred "isolated" to the ambient air without heating up anything else during this process. Of course , heatsinks on the power circuit will not going to do any harm, but it's not going to improve your overclock. They can be helpful when you are really stretching the card limits with very high voltages.

EDIT: ATI 4850/4870 volt mods can be found here http://www.xtremesystems.org/f...ad.php?t=190990&page=3

The easiest and maybe the "safest" vmod is the pencil one, since it can be erased and it won't leave any scars on the card.

I actually found another way to volt mod it. http://www.xtremesystems.org/f...howthread.php?t=193774. IMO it's a lot simpler and it seems to work. I can get mine up to 700MHz with no artifacts in ATITool now. I'm not sure if I should push the voltage on the memory though as I have no way of measuring the temperatures. Do you know of any programs to monitor the memory temps with and what is a safe range for the memory?

 

[error8]

Wow, volt mods are so simple these days. I don't think you can measure the temperature of the ram chips and even if you did it wouldn't help you too much. I don't know what to say about a safe voltage range for the memory. You can leave it as it is and just overclock it on stock volts. It's a pain in the butt to volt mod the memory anyway, since you can hit severe instability even with the slightest voltage increase, like artifacts in windows in 2d mode.

 

[octopus41092]

Originally posted by: error8
Wow, volt mods are so simple these days. I don't think you can measure the temperature of the ram chips and even if you did it wouldn't help you too much. I don't know what to say about a safe voltage range for the memory. You can leave it as it is and just overclock it on stock volts. It's a pain in the butt to volt mod the memory anyway, since you can hit severe instability even with the slightest voltage increase, like artifacts in windows in 2d mode.

Ok, and how would I measure the voltage to make sure it's running at what it's supposed to? Are there any programs or do I have to use a multimeter.

Also, I heard that you can overclock past 700MHz using AMD GPU Clock Tools rather than flashing the BIOS, but I haven't been able to get anywhere with that. When I try to change the clock speeds with that it says "SetClock failed! Please check device configuration."

 

[octopus41092]

Ok, I don't know whats wrong, but I still can't seem to get it to finish 3DMark06 without crashing when it's overclocked. I did an artifact scan on ATITool, and it can go on for hours without any artifacts. However, in 3DMark06 I can only complete maybe the first one and then the screen will go black then I'll get vertical colored lines. Anyone know why this might be? Also I still need a program to monitor the voltage and I still don't know how to get AMD GPU Clock Tools to work. Help please...