is it harmful to underclock video card?

Jetster

Member
Aug 1, 2005
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a newb question here, my 6800gt seems to run very hot(high 60C while idle), while i'm waiting for a new cooler, i like to bring the temp. down a bit for now. So will adjust the 2d clock freq. (I assume it's the idle mode, correct?) to a lower value in Coolbits helps? if so, is it harmful to the video card? thanks for any input
 

Azndude2190

Golden Member
Jul 4, 2005
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Try it.But dont go to low....just do it in increments and monitor your temps.I doubt anything bad will happen.
 

Steelski

Senior member
Feb 16, 2005
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should have no problems at all. infact i think it would be supported by Nvidia. is there a tool that can flash your bios to a lower voltage. you might be able to do that if you can bring the mhz down low enough.
 

xtknight

Elite Member
Oct 15, 2004
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You'll want to lower the voltage if you lower the clocks. Otherwise the high voltage may possibly cause problems...I don't know. Unfortunately I don't think there's volt adjustments for 2D and 3D individually.

I had my friend with a artifacting 9800XT downclock his card 200 MHz. Didn't hurt the artifacts but didn't help them either so it's hard to say. It's probably safer to leave your card at 60C than to try and downclock it. 60C isn't that high. As long as you don't game on it, leaving it idling at 60C should be just fine. My 6800NU has load at 60C and I've been using it for a year without damage.
 

mwmorph

Diamond Member
Dec 27, 2004
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underclocking too low will artifact your video card. i tried my 9800pro/xt at 250/500 and artifacts showed up like crazy. i keep it at 350/650 for 2d and 440/760 for 3d now.
 

narcotic

Golden Member
Jul 15, 2004
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it's true some people here are getting great low temps from their cards, but usually a vid card can easily deal with ~90c so I wouldn't really worry about it ideling at high 60's.
Though you might want to avoid OC'ing at this point (untill you get a better cooler).
 

CraigRT

Lifer
Jun 16, 2000
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I am going to not answer your question directly, but suggest you just leave it as is. The cards run that hot, it's not a problem, it's the way they are. It's designed to take temps higher than that in extreme cases, so I wound't worry about it til you get a new cooler. But thats just my .02.
 

Captante

Lifer
Oct 20, 2003
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I always underclock my 6800GT when I'm not gaming (300core/900ddr) and it runs considerably cooler.. been doing it for a long time with no problems at all. The card does run pretty hot all the time though.. mine is around 64c idle at default clock & upper 70's/low 80's in games when OC'ed to Ultra speeds.
 

Captante

Lifer
Oct 20, 2003
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Originally posted by: orangat
Only 300? I set my 2d clock at 150.

For some reason my card doesn't like being clocked below 280mhz core... doesn't lock up or anything but I get some visual glitchs on the desktop.. could be because its an early GT but thats just a guess.
 

hans030390

Diamond Member
Feb 3, 2005
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To a point, underclocking can harm your card, but if you do it by just a bit it wont hurt it.
 

Unkno

Golden Member
Jun 16, 2005
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wow.....i never knew that 6800s run so hot....my X800GTO2 unlocked and clocked to a X850XT only idles at 36C and loads at 65C
 

Acanthus

Lifer
Aug 28, 2001
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I took my 6800GT down to 150mhz core in 2d and 200mhz core 3d, it reduced my temps by about 12C load until the replacement fan was here.
 

lifeguard1999

Platinum Member
Jul 3, 2000
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If your card is idle at 60C, I would recommed taking a look at the heatsink to make sure it is attached well. My card idled at 47C and maxed out under load at 92C (with no problems). However, I felt that the heatsink must not be doing its job to be running at 92C under load. So I took it apart and placed it back on. Now it runs at 62C under load (and 42C idle). Look for the obvious problems first.

Will underclocking your card hurt it? No, it won't.
 

Goi

Diamond Member
Oct 10, 1999
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Does anyone know if video playback constitutes 2D or 3D mode? In overlay it's probably 2D, but I'm using VMR9 output which I believe uses the pixel shaders, so is it considered 2D or 3D?
 

Eureka

Diamond Member
Sep 6, 2005
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60°C seems right for a nVidia 6 card, my 6600Gt runs at like 50-60 idle.

Norm
 

orangat

Golden Member
Jun 7, 2004
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Originally posted by: Goi
Does anyone know if video playback constitutes 2D or 3D mode? In overlay it's probably 2D, but I'm using VMR9 output which I believe uses the pixel shaders, so is it considered 2D or 3D?

2D of course. Although I'm not sure about vmr9 since I haven't used it.
 

DrZoidberg

Member
Jul 10, 2005
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my leadtek 6600gt extreme (factory overclock) is currently 37C idle according to coolbits, on hot days it can get up to 45C idle. On full load like playing CS source it will reach 60C-high 60s.

Dont worry about underclocking as gpus can take up to 90C (on load). However 60C idle is not a good idle temperature if u plan on not improving your cooling and leaving it for years. My case has 2 120mm fans and a side 80mm fan. According to AT 6600gt review some 6600gt have bad heatsink sitting so u could check that.
 

Acanthus

Lifer
Aug 28, 2001
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Also, if you have the reference cooler, take off that cover on the heatsink (eyeglass kits work grea) and check for clogs, that cooler tends to pack dust between fins and stop airflow completely.

Ive seen it to the point were you can actually pull all the dust out in one big chunk because its packed in so tight, and temps immediatly dropped 30C, it was blocking ALL of the airflow.
 

xtknight

Elite Member
Oct 15, 2004
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Originally posted by: Goi
Does anyone know if video playback constitutes 2D or 3D mode? In overlay it's probably 2D, but I'm using VMR9 output which I believe uses the pixel shaders, so is it considered 2D or 3D?

2D for Overlay and 3D for VMR9. However, most VMR9 3D processing is not heavy enough to warrant such high idle clocks on a video card. Usually there's no 3D processing at all except for DXVA.
 

Goi

Diamond Member
Oct 10, 1999
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So am I right to say that once I start playing VMR9 video, the GPU clockspeeds will increase to what's set for 3D mode?
 

xtknight

Elite Member
Oct 15, 2004
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Originally posted by: Goi
So am I right to say that once I start playing VMR9 video, the GPU clockspeeds will increase to what's set for 3D mode?

I'd think so, but I'm not sure. Maybe only in VMR9 renderless mode. Depends if NVIDIA classifies VMR9 as '3D' or not; I don't know if they do.

Easy to test using RivaTuner's system monitor.