Overclocking – AdvancedNow that you have found the maximum frequencies for your video card’s Core and Memory, you can begin experimenting with the voltages if you understand the risks.
Voltage selection in ATIToolCore Voltage (VGPU)
I suggest using .025v increments at every stage. Once you make the increment, increase your Core’s frequency by 5MHz-7MHz and use the testing procedure mentioned before. I strongly suggest you do not use higher voltage increments while testing, because these minor voltage increases will increase the heat output of your video card significantly. I do not recommend going above 1.50v with air-cooling, but you may wish to try higher if you think your temperatures are reasonable.
Do not forget to overclock and retest your memory again. The video card’s memory seems to benefit from increases to VGPU as well.
Memory Voltage
The 3 voltage settings available in ATITool (MVDDC, VDDQ and VDDCI) are all related to the video card’s memory and they impact the overclockability of your RAM (some more so than others). This is not like VGPU where you can just raise it and get a linear increase in clocks. Sometimes it will help to go up, sometimes it will help to go down, and each setting varies as well. I feel what is suggested here will help you get the most out of your video card’s memory.
RAM Chips Voltage (MVDDC)
The main theme for this setting seems to be “increase” when using ATITool. Because ATITool does not change timings, an increase in memory voltage is the only way you will be able to increase your memory clocks. On the other hand, AO relaxes timings, and a lower voltage maybe of benefit to you.
This is the setting I suggest you tweak first: use .005v-.010v increments in ATITool to increase your MVDDC and then increase the Memory frequency 10MHz at a time (using the testing procedure suggested in the previous section for overclocking the memory) until you cannot go any higher. Increment the voltage again and repeat. Once you no longer see any increases in frequency from increasing the voltage, you may try smaller voltage/clock increments and find your absolute maximum memory frequency.
Memory Buffers Voltage (VDDQ)
Once you have found your video card’s memory’s maximum clocks from an MVDDC increase, you may turn your attention to the next available memory voltage setting: VDDQ.
Now this setting seems to be a little strange and I have not found any consistent results with it. But it seems like the most likely thing that needs to be done here is to decrease the voltage the memory buffers receive. I suggest you keep 3D View open, and begin lowering VDDQ. Pause for at least a minute between each decrease and then proceed. Once you start seeing artifacts or your computer hangs, you know you have found the limit of your VDDQ. You may try increasing your memory clocks again just to see if you have gained anything from lowering VDDQ, but you will most likely not see any kind of increase in overclockability of your RAM.
Lowering this setting helps reduce the amount of heat generated by your video card as well as reduce the amount of power required to operate your card (the decrease in temperature maybe enough to allow your memory for a few more MHz).
An alternative would be to keep VDDQ similar to MVDDC or even keep it around VDDC+/- 0.010v. You may test both to see which suits your needs better (it might be that a lower VDDQ and a higher memory clock maybe beneficial to a higher benchmark score, rather than a more stable, lower, memory clock).
VDDCI
The last and most mysterious of them all is VDDCI. Some say it’s some kind of gatekeeper for the x1900 cards, but we don’t have any concrete evidence or enough information to accurately predict the function of this voltage.
Experiment with VDDCI from 1.550v to 1.580v. You can try various settings in that range until you find the voltage that suits you. Do not be surprised if you see the RAM go up another 20-30MHz, as this is to be expected with a high VDDCI.
A VDDCI of 1.563v seems to be a favorite for some and 1.580v for others. ATITool may complain and say the voltage is too high, but I haven’t found any problems (as well as many others) with running it that high.
A note: Remember that the memory chips on your video card are very sensitive components, and sometimes a voltage difference of 0.001v maybe enough to allow your memory to overclock much higher. I will recommend using as small increments as possible with all the voltages related to your video card’s memory. This will depend on how patient you are and how much you are looking to getting out of your video card from overclocking.
You can now test for the new maximum of your video card’s memory by repeating the process suggested before when overclocking your video card's memory.
Crossfire, CCC Overdrive and a few extra tips on the last page ->
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) with a x1900xt card and an amd s939 3700+/4000+, 2gb pc4000 ram, 1 sataII HD.
I've tried using the method (with different voltages and settings, of course) on my X1800XT but when I push the core above 640, video locks up--whether using WMP or MP Classic.
None of the reviews I've seen ever mention playing video after all the overclocking. There's an open debate on this over in the Rage3D forums.