Does Temperature Affect Overclocking?

[DavidNJ]

That is, can you run a higher clock at 50C than 65C? Many of these cards run fairly hot. Does juicing the fan or putting them on water let then run faster or just add safety margins?

Also, does water cooling the memory help? Full cards watercool the memory. Modules like the Dtek GFX Fuzion that can be used on different cards use heat sinks on the memory. And even an EK or other full card uses a heat sink on memory on the reverse side of the card.

What is your opinion AND experience?

Thanks!

[moogle]

Yes temperature does affect it. If it's too hot might get artifacts/errors at speeds that you wouldn't if the GPU was cooler. When it's under water it keeps it cooler and allows you to overclock more. The memory chips always have to be cooled especially if you're overclocking. The full blocks usually don't have alot of fine fins to create turbulance in the water to remove more heat, but it does cool the whole card. Those multi GPU coolers like the D-Tek, EK and Swiftech blocks have lots of fins which are more restrictive and do require the memory chips to be cooled by putting those little heatsinks on them, but this cools the actual GPU down more than the full cover block.

The only reason that EK block uses a heatsink on the other side of the card is because there are memory chips on that side too.

[DavidNJ]

I realized that about the EK block, using it to point out that they only air cooled half the memory.

Dtek has a large combined heat sink for the GTX, I think iandh has something for the 4870. I don't know of any solution for the 4870x2, 4850, or 4850x2. On most 4850s and some 4870s there seem to be no cooling provisions for the memory.

I will juice the fan and try again...

[Plan.B]

Yes, temperature affects overclocking. Generally speaking, within the limits of each chip/processor, lower temp = higher overclock; and higher voltage = higher overclock. Increasing voltage increases the temp of the chip/proc. Increasing the speed of the chip/proc also increases the temp. Ideally you combine a higher voltage and a lower temp and you run the chip/proc reliably at faster than stock speeds.
Every chip/proc is different, and there are other factors affecting overclocking.

[DavidNJ]

Is there a way to adjust video card voltages without soldering a rheostat on it?

[dengyong]

Is there a way to adjust video card voltages without soldering a rheostat on it?

Usually not, and pick the water block you like best because your clocks will be the same.

[STEvil]

depends on the video card, but generally the adjustment is very small.