Doug's Quiet Wood Case: Reloaded

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Gorsnak
Posts: 190
Joined: Sun Nov 23, 2003 6:27 pm
Location: Saskatoon, SK

Doug's Quiet Wood Case: Reloaded

Post by Gorsnak » Sun Sep 03, 2006 2:27 pm

So, the upgrade bug bit me, and I retired the old Socket A system (temporarily) in favour of an almost completely new build. Only the optical drives and peripherals have been held over. The new goodies:

AMD X2 3800 AM2 w/ Thermalright HR-01
Asus M2N-E motherboard
Corsair 2x1GB TwinX DDR2-800
PowerColor X1900GT w/ Zalman vf900
WD SE16 Caviar 250GB
Seasonic S12-430 psu

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The 120mm Nexus fans on the CPU and exhaust are running at 750rpm and 810rpm respectively (same voltage, so evidently the orange ones are a tad faster), which gives me CPU temps of ~35 at idle and ~55 under load. I tried leaving the CPU fan off and running the HR-01 passively, but the loaded temp was getting into the high 60s and still climbing (albeit very slowly at that point) when I shut down the test. I got the flexible duct for it, but my exhaust fan is too far offset from the heatsink to make that work, and I'm not overly inclined to go to the bother of building a custom duct.

The gpu with the stock cooler was idling around 60 and peaking at around 90 under load. With the fanmate turned to max on the vf900 it idles in the high 30s and peaks in the mid-50s. That's noisy, though, so the fanmate is turned all the way down, giving me idle temps of mid to high 40s and peak temps playing Oblivion at around 65.

The one slight temperature issue is the motherboard. The base of the heatpipe northbridge cooler gets rather hot, what with the fins of the cooler being in a bit of a deadspot, airflow-wise. I can hold my finger on it for about 2 seconds, which likely puts it around 70-80, higher than I'd really prefer. A makeshift deflector intended to divert about 30% of the cpu hsf airflow over the mobo heatsink had no discernable effect, so I'm still debating what I can do to improve the airflow in that back corner.

Noisewise I've lost some ground. The machine is still very quiet, but it's now emitting a hum that's audible from ~1', or from my chair on those rare occasions when neither the fridge nor the waterpipes are making any noise. What's happening is that old fan vibration/wood resonance bugbear. Both the cpu and gpu fans are not isolated from the case, and I'm getting some resonant humming from that. I have not yet decided whether I'll do anything about it, as it's rarely audible and even when it is the sound isn't particularly unpleasant. Isolating the cpu fan would be easy enough, but the Zalman would be tougher, though just removing the fan and sticking an 80mm L1A over (under?) the heatsink might be doable.

Next up: the old hardware is going to be set up as a Linux/MythTV htpc box. Yes, that's right, it's going to be Doug's Quiet Wood Case MkII: HTPC Edition, with a design thread coming soon to a cases forum near you.

cAPSLOCK
Posts: 224
Joined: Fri Sep 16, 2005 11:06 pm
Location: Switzerland

Post by cAPSLOCK » Mon Sep 04, 2006 1:03 pm

For the northbridge problems, maybe leaving the I/O shield out, or making a hole there will help, three possibilities of what will happen:
1. Air will be sucked in through the hole and past the NB heatsink
2. Air will be sucked in through the hole and back out the extract fan, then you will need to make a deflector or duct of some sort
3. Air from the CPU fan will "find it's way out" through the hole, and thus pass through the NB heatsink, currently this doesn't happen since there is nowhere for the air to go.
There must be some way of decoupling the CPU fan, hanging from elastics or else mounting on silicone cushions, the gfx fan is harder, but probably possible to put some silicone grommets between the fan and the heatsink.
Anyway, nice setup! 8)

Gorsnak
Posts: 190
Joined: Sun Nov 23, 2003 6:27 pm
Location: Saskatoon, SK

Post by Gorsnak » Mon Sep 04, 2006 3:32 pm

Actually a post in another section here gave me the idea of isolating the mobo tray/backplate from the rest of the case using rubber grommets. That might be enough to solve the resonance issue. If I decide it's worth the effort - there really isn't a lot of noise coming off the thing. And you're right, it'd be really easy to isolate the cpu fan, just replace the wire clips with elastic cords and put some foam between the corners of the fan and the heatsink.

Removing the I/O shield is an interesting idea. I hadn't thought of that. I was considering trying to mount the cpu fan "lower", i.e. closer to the mobo, so that there'd be some fan wash going past the heatpipes towards the mobo heatsink. I'd expect an open I/O shield would have that acting as an intake, which would be good for the motherboard, but not so good for airflow in the lower part of the case. Some experimentation is probably in order.

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