SPCR

I just dropped my 5900Ultra from 300mhz to 75mhz in 2D with no ill effects.

With passive cooling, that translated to about a 5C drop.

Not too shabby for something that cost precisely nothing.

I underclock my 9800xt from 412/365 to 225/250 in 2D. If I go much lower on the core, atiTool shows artifacts so that'll have to do. It runs quite a bit cooler, but only cool enough for me to run it with the fan on minimum...still needs the fan.

I'm currently running my 9800Pro at 150/150 with completely passive cooling, without any artifacts, and with very low temperatures.

eclipsevv wrote:I'm currently running my 9800Pro at 150/150 with completely passive cooling, without any artifacts, and with very low temperatures.

Hi, eclipsevv. Welcome to SPCR Forums!

What application are you using to underclock your 9800Pro?

What sort of passive cooling are you using? Did you replace the stock HSF, or did you disable the fan?

I have a 9800Pro as well, running at 200/200 with a VGA Silencer on low.

Ditto, been running my X800XT at 235/235MHz in 2D. Lets me get away with 20% on the stock fan at 50C, slow enough that it stops rattling. Haven't bothered replacing it since my case is good enough to cope and I have other plans soon.

Still kind of annoying that it won't underclock much further without artifacts piling up; 235MHz on a current card is still like 100x overkill for a single-monitor Windows desktop.

lenny wrote:What application are you using to underclock your 9800Pro?

What sort of passive cooling are you using? Did you replace the stock HSF, or did you disable the fan?

I'm using ATItool; 150/150 is the default, it switches to 378/338 on 3D, then gets back to 150/150.

I'm using a Zalman ZM-80C passive heatsink; it becomes quite hot during gaming (378/338), but remains at about 30-35°C when underclocking.

Usually I increase voltage to the case fan in case of prolonged gaming (I have a rheobus).

Util I just downloaded called Nibitor allows you to set clockspeeds and voltages via the BIOS

I hope it doesn't fry my card

How does it work? Can you set your card at the BIOS level to underclock/undervolt for 2D, then run stock (maybe even undervolted) settings for 3D?

Yep, you can.

And it seems to have worked.

Took the 2D voltage down by .1v, and underclocked it to 100/500

In 3D it runs at stock.

It's running 6C cooler now.

Makes the 6600GT even more appealing. Thanks for the info.