nexus fan replacement raises gpu temps 20C... advice?

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Shaft0rz
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nexus fan replacement raises gpu temps 20C... advice?

Post by Shaft0rz » Mon Feb 07, 2005 6:55 pm

Hey all,
So I replaced the Antec Tri-Cool and the zalman fan in my 7700 with nexus 120mm. The results are very silent, however the temperatures in my case have gone up substantially. My gigabyte passive 6800 went from 50-55C to ~70C. I tried closing up the front intake, so most air was coming in from the side bottom vent, blowing directly on the 6800. Temps went down modestly (a couple degrees), and hard drive temps went up (from ~30C to 37-39C). Any advice on which of these two scenarios is ideal? I'm leaning towards letting the video card stay hotter (it seems to remain stable).

Also, could the nexus fans really drive gpu temps up ~20C? That seems a little extreme. I'm wondering if there are other things messing up airflow that I didn't notice in switching out the fans, like re-arranged cables or something.

Any advice would be helpful

Thanks!
Peter L.

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Post by Ralf Hutter » Mon Feb 07, 2005 6:59 pm

Sure you haven't put the new case fan in backwards?
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air flow, air flow, air flow....

Post by NeilBlanchard » Mon Feb 07, 2005 7:02 pm

Hello:

You could dress your cables -- if they are messy and you get 'em really neat...that help a little, especially if there is a dead spot near the video card. High HD temps are *not* good.

Are you fan grills snipped out? What is the intake like? Are you undervolting the Nexus on the exhaust? What about a better passive vid HS? Or the Zalman?
Sincerely, Neil
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Shaft0rz
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Post by Shaft0rz » Mon Feb 07, 2005 7:05 pm

I just thought about that too, so I checked. The nexus is definitely blowing out of the case. If it makes any difference, here's my system:

seasonic super tornado 400W
antec 3000b
a64 3200+ (winchester, 30C)
zalman 7700, fan replaced with nexus 120mm (running at 5v)
2xsamsung spinpoints, suspended in front
gigabyte 6800 passive
m-audio delta 1010LT soundcard
nexus 120mm case fan exhausting out back (right now running at 12v)

I just unblocked the front intake. Sitting at idle, my temps are:
ambient- 16C
mobo- 29C
cpu- 29C
6800- 69C
hd1- 33C
hd2- 31C

Shaft0rz
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Post by Shaft0rz » Wed Feb 09, 2005 11:53 am

Follow up:
I re-arranged some cables to make a clearer path for the air, closed off some other places for air to enter the case, and blocked the non-filtered portion of the front intake in my 3000b (to allow some air to enter for hard drive cooling, but increase the pressure so more air comes in the side vent). Also, I moved my m-audio card down to the bottom-most PCI slot, so it doesn't block any air to the 6800.

These simple changes have lowered temps from 69-72 at idle to ~61C at idle. Load temps (after a couple runs of 3dmark 2005) are down to 68C.

I still need to get rid of the fan grills, but I'm very, very pleased with results from a simple cleaning up of cables and some redirection of airflow. Thanks for suggesting that.

Shaft0rz
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Post by Shaft0rz » Fri Feb 18, 2005 4:57 pm

Here we go again... after some time running at lower temps (60 idle -> 68 load), my 6800 has gone up drastically in temps again. It now idles at 70C and goes up to 80 at load. Nothing changed in the system, all that I did was cut the grills on my 3000b. What gives? I've checked for dust, and there isn't any. I tried moving my nexus 120mm from the rear to the front to get more air to the 6800, with no results.

Does anyone have any idea why my temps would change so drastically for no apparent reason?

EDIT:
Forgot to mention-- the top heatsink is barely warm to the touch, while the heatpipes are SCALDING hot and the bottom heatsink is quite warm. Do heatpipes lose efficiency over time or something?

I also just tried taking that nexus 120 (at 12V mind you) and holding it blowing DIRECTLY on the 6800 bottom heatsink (the warmer one). It only got down to 58C. Ambient is 15C!

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Post by acaurora » Fri Feb 18, 2005 10:09 pm

I dont mean to say your video card is bad, mind you I have a 6800 Ultra (Watercooled), but perhaps the cooling solution isn't really meant to be fanless? I mean a 6800, come on. Top of the line video card, sizzling hot... go figure. It might just be the heatpipe solution Gigabyte chose to go with that isn't too great. There are other heatpipe solutions out there for 6800s as well that do better, Edward Ng has one on his, although I don't remember the model/brand. One other thing you could try is using a cyclone blower in a free PCI slot - there are a few that I have tried that are pretty quiet yet do move a lot of air. If cyclone blowers aren't your thing, then I believe you could try some sort of ducting with the VGA vent in your 3000B. The grilles aren't very restrictive, from what I've seen, so taking them out is something I don't believe is absolutely necessary. And that Tri-Cool I think is perfectly fine. If you no longer use it, I'd gladly take it off your hands. ;P
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Shaft0rz
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Post by Shaft0rz » Sat Feb 19, 2005 6:48 am

You might be right about gigabytes heatpipes. It just might not like have no fan. I suppose it's nice that now I at least have a choice of what fan to use and where to put it (as opposed to an integrated one), however it's a bit frustrating. For now I'm running OK, after having overclocked the chip to 380 in 2D, and 365 in 3D (see vga forums for my post). Load temps still approach 80, but I've seen temps like that around for OC'd fanned 6800's. So while they're not great, I can deal with it, for now.

I've got to say though, cutting the grills on the 3000b can make more of a difference than you might think. It dropped idle temps on my a64 3200+ about 5C, and load temps about 7C. With cpuburn I max out at 38C, which used to be around 45C. So don't underestimate how restrictive even seemingly open-looking grills are :)

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Post by acaurora » Sat Feb 19, 2005 12:45 pm

Well I cut the grilles off my 3700BQE, didn't really notice a big jump in temps, just say a degree or so. it probably is a more substantial difference for you with the whole side vent thing. I'm sure that you can somehow create a vent that ducts from the side onto your heatpipes, it shouldn't be that hard. Just buy a Zalman fan mount, use some kind of ducting tubing, and voila.
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Post by David Mitchell » Mon Feb 21, 2005 5:35 am

Shaft0rz wrote:Forgot to mention-- the top heatsink is barely warm to the touch, while the heatpipes are SCALDING hot and the bottom heatsink is quite warm. Do heatpipes lose efficiency over time or something?
I'm not experienced with heatpipes, but I recall that some of them don't work unless they are properly oriented. You don't have your case on its side, do you?

(No offense intended — I know this is pretty close to "Is your monitor plugged in?")

Shaft0rz
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Post by Shaft0rz » Mon Feb 21, 2005 8:09 pm

Haha, none taken.

Nope, the case is upright. I seem to have sorted things out but moving the 120 mm fan from the exhaust to the side vent of the 3000b. I cut out some extra metal to make a hole for the fan, and mounted it blowing in. At 380mhz, the video card idles at 44C, and load goes up around 65C max. I was worried about the hard drives with no cooling (and no air being sucked in directly on them), but they seem OK at 27 and 29 (even during defrag). PSU fan (super torndado 400) stays inaudible, and I am running both other fans at 700. CPU maxes at 40 and idles at 24. Seems to be working out.

I'm still confused why temperatures were soo variable with this card though. It went through 20C swings, mostly at random (or at least it seemed to be).

Thanks for all the suggestions everyone. I really appreciated them.

Peter L.

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Post by Oliver » Wed Feb 23, 2005 5:04 pm

Interesting posts about your system.
I have no experience on any of this, but have read a lot.
It is obvious from your description, that you need some turbulence over the radiators of the graphics card cooler.

The pipes of a heatpipe certainly can be hot as the evaporated liquid condenses at the radiators and drips back down along the walls of the pipes leading back to the GPU core. Of course the liquid heats back up at the core and evaporates going up the center of the heatpipe and warming the just cooled condensed liquid. So I can see the pipe section being hotter than the radiating fin section. There seems to be some logic in that.
Some sort of equilibrium of the two processed I described will be reached at the pipe area. That is my understanding from what I have read about heatpipes.

I guess your cpu cooler is not designed for the fan to blow away from the heatsink and processor?

But maybe its air pattern could be concentrated if you reversed the fan (so it blows towards the side panel away from the motherboard) and put a shroud around it that captured the air and then angled it at the graphics card's passive cooler. You got to get some turbulance there. I realize that you would be blowing slightly warmed air at it,but maybe you could design the shroud to mix in some other air before it hit the graphics card.
I think the modern amd a64 processor will automatically trottle back or shut down to protect the core processor if it get too hot. That way it won't irreversibly damage itself from an intense heating. So you should technically have some safety margin to experiment in flipping the fan over on you heatsink.

Oh, you can put the original heatsink fan back on, and see if your graphics card restores it orignal temperature range. I can tell from you post you seem to be wondering slightly whether it might still be in original condition.

Anyways, take everything I wrote with a grain of salt. I really have no experience, just bunch of reading, and would not want you to damage your system.

Only thing I would say for sure, is you need some turbulance over the passive graphics processor.

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