Cooling the chipset / ASUS M4A78T-E

Northbridge, Southbridge, PCI-E chip, and VReg water blocks...
GMOTSL
Water Pistol Grunt
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Cooling the chipset / ASUS M4A78T-E

Postby GMOTSL » Sun Aug 30, 2009 8:26 am

I replaced the stock AMD CPU cooler with a CPU-350, but I did not use any NB/SB water coolers. I applied one of the Exos temp sensors to the passive heatsink for the the 790GX chip. The Exos reported this sensor showing well in excess of 55C, and then shut my system down (grrr). After I disconnected this sensor (to avoid a shutdown), I checked the motherboard-reported temps. My CPU (955BE) is idling around 36C and the mobo is sitting at 46C. The ASUS PC Probe 2 software allows a max chipset temp of 60C before triggering alarms, so I'm hoping I'm at a safe level with this passive cooling.

I had thought that the "exhaust" from the stock CPU fan would direct air towards the 790GX heat sink, which might cool the chipset. But the orientation of the stock heat sink's fins would force air left/right (relative to the CPU), and not up/down (towards the 790GX). Regardless, this would still help stir the air inside the case, and now I've lost that effect. I'm left with the PSU's 120mm exhaust fan, a rear exhaust 80mm fan, and two 80mm intake fans at the the bottom front of the case.

I'm wondering if I should be worrying about the chipset temps. I am a bit concerned that the Exos temp sensor reported as high as 65C (when the forced shutdown occurred) while the mobo BIOS reports 46C. The Exos temp sensor for the CPU actually does report a temp close to what the BIOS reports (31C vs 36C). I would really really prefer not to go down the path of water cooling the chipset. The M4A78T-E chipset heatsink is pretty big though, so I'm not sure how I could improve it w/o going to some active cooling :| I've water cooled the GPU, so for now, I think I'll cover up the no-longer-needed exhaust vents at the back of the vid card. My hope is that this forces the air brought in by the intake fans to go up through the case, past the chipset, and not take a shortcut out of the case via the back of the unobstructed vid card vent.

Many thanks for your thoughts..

bambihunter
Water Cannon Artilleryman
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Re: Cooling the chipset / ASUS M4A78T-E

Postby bambihunter » Mon Aug 31, 2009 10:02 am

Did your board not come with a small fan that clips on the chipset heatpipe's heatsink?
*edit, I just looked and they don't*

I have a HTPC that I had problems keeping the NB chipset cool even though it had a 120mm rear exhaust fan fairly close to it. So, I used some cardboard (like from the back of a notepad) and cut, glued, and taped it to a shape that pulled a significant portion of its air from the NB and a little bit from the V-reg's. My chipset now stays about 41c under normal use and up around 44c while folding.
It is a tad crude looking, but it works great. I needed that particular PC to be quiet so rather than speeding up the fans, or adding more I just made that funnel. If a person wanted, they could have someone make something custom either out of fiberglass or sheet metal. Another idea is to put a fan and/or fan duct blowing directly in where you need the air flow. The last, and most obvious choice would be just to water cool your chipsets. Since it is a non-heatpipe design you should be able to do just the northbridge and leave the rest alone.
PC5-1336BK
PSU-1300ATX
2 VID-NX295S
2 RP-1000
RP-980
CPU-350AC
2 CHC-122
MVR-100
AMD 955BE, 6 250gb in RAID0, 8GB OCZ Flex 1200, 2 EVGA GTX295 FTW's. Loop 1: CPU & quad GPU's. Loop 2: PS to 120mm to NB/SB/Vreg's to dual 80mm rad/fans

GMOTSL
Water Pistol Grunt
Water Pistol Grunt
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Joined: Sun Aug 30, 2009 7:28 am

Re: Cooling the chipset / ASUS M4A78T-E

Postby GMOTSL » Mon Sep 07, 2009 10:31 pm

Update:

I've decided against using water cooling for the NB and SB chips. Adding chipset blocks would seriously clutter my midtower case with tubing (I'm running with 13mm). I've noticed that only the NB is really hot. The heatsink over SB chip is a strong warm to the touch, but not hot. It's situated where the case fans from the front direct air past it. The mosfet heatsink is cool to the touch, but they're conveniently located right next to the case exhaust fan. I've decided to go with a TR HR-05 IFX heatsink, and try running it passively.

I had also considered slot-mounted fans, but the top-most slot opening in my case is actually blocked by the NB heatsink, and the slow below it is occupied by the gfx card. I next considered screwing a small 30mm/low speed fan to the top of the stock NB heatsink. I think that would work ok, even if moving only a tiny amount of air. I decided against this because it'd probably not work any better than "ok." I'm going to hope the large, passive heatsink approach works, possibly in combination with a funnel of some sort as suggested.

Thanks!


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