Zalman not needed for 7900GT voltage mod

[rogue1979]

Picked up a 7900GT from another forum member for $90. It was a cheap upgrade for my aging but still decently fast X850XT. Been playing GRAW2 lately and I can definitely see the difference between no HDR (my X850XT) and HDR turned on (my son and daughter both have 1900GT's @ 1900XT speeds).

Did a hardware mod to 1.4v for the gpu and proceeded to overclock to 610/1800. It was reaching 80c under full load and the stock EVGA fan would really make a racket. Figured I would order a Zalman from newegg, but since it was the weekend I would have to wait until Monday to order and perhaps Thursday for delivery. Being my usual impatient self, I set out to solve the problem right away.

Had a 120mm fan that I had never needed to install in my case cuz the X850XT stock cooler dumped the excess heat outside the case (was a little loud under full load, reasonable quiet in 2D). Got the dremel and installed it low on the side aimed right at the video card. Pulled the stock gpu cooler, cleaned it, lubricated the fan, applied silver thermal paste and slapped it back together. It worked, idle temps went from 60c down to 52c and load temps from 80c down to 70c. Still way too noisy for my taste. Modded the bios settings for fan control to 35% 2D and 75% 3D. With the 120mm (7 volt modded) the temps stay about the same, but still loud in 3D.

Took the cover off (and left if off) the nice shiny gpu heatsink and replaced the fan with a thin 70mm that covered the entire heatsink. Since both fans were rated at about the same amps, hooked it up to the gpu fan header. Flashed the bios again to 35% 2D 60% 3D and put in the overclock speeds as well.

Success!!! 67c under full load, 60% fan speed is not audible over the power supply (Quiet 120mm Fortron Source). At 7 volts the 120mm side fan is also silent.

No Zalman needed for a couple of hours of work and about $8 worth of fans.

Managed to break the 10k barrier in 3Dmark 05 with a A64 3200+ @ 2800Mhz.

[Reign]

that's cool, you have pics of your mod? i got mine up to 600/825 24/7 with zalman and 12cm side fan and mine reaches mid 50's at full load lowest fan settings. (my 7900gt ran 560/825 default though)

[rogue1979]

Here is a link to the 1.4v mod.

http://forums.guru3d.com/showthread.php?threadid=176625

I simply used a soldering iron and some low temp solder to make the trace on the red line.

The core on my GT is kind of weak, most people seem to be getting 650Mhz on the core. Since you have already reached 600 and have good cooling, you should be able to nail it. The core voltage mod seems to allow more memory overclocking also, even without doing the vdimm pencil mod which seems too iffy for me to try. If they had a set resistor mod to solder on I would definitely give it a try.