Dual Xeon silent cooling system

[pm.stacker]

Some homemade ducted PWM cooling system for my Nehalem-EP workstation it may be not that good and not ultra-tailor made but it works somewhat good preventing PSU from taking in the CPU0 heat. Setting 30% min RPM (560 RPM) yields 45°C (113°F) idle temp, 45% (780 RPM) takes that down to 42°C (107.6°F) and never goes up on 100% load. Setting 60% (1000 RPM) makes the fans somewhat "loud"

The two Enermax UCCL12 fans work in push-pull symmetrical mode (push-CPU1-duct-CPU0-pull), the rear Scythe SL1225L12L-P works as "ducted" (recycled Silenx 38mm frame) exhaust with slightly higher RPM than the UCCL fans to create a little neg (it should catch up all air coming from the white fans).

 

[jedimasterben]

That's really cool. Have you thought about making some sort of shroud on the coolers themselves so that the air does not flow out the sides and passes straight out the back?

 

[pm.stacker]

I have some plastic sheets I could cut to make some sort of "air channel" similar to those you find on high-end workstations and servers, but they're black so they'd cover up all the "machinery" and since I have the transparent side panel that wouldn't be cool (I ain't an extreme modder but a little flash's always welcome ) . I thought about putting a "heat shield" on top of the CPU1 heatsink too, to prevent little air from going out of the duct and to the PSU, I'll try this. For the air escaping from the top and bottom sides, it is very low (Noctua NH-U12DX heatsinks are not full of transverse holes like i.e. the Thermalright HR series). For air escaping from the left and right sides (that with a vertical mounting like mine become top and bottom), it depends on the fan. The fin sides let some air out, but in vertical mounting it becomes something like a chimney effect: warm air tends to escape only from the top drawing cool air from the bottom (I use this to slightly enhance passive cooling on the GFX card, which sits in slot1 near CPU0). Having a high static pressure fan with a straight frame makes the difference in enhancing a straight flow through the heatsink. Fans with rounded frame edges tend to lose some air out of the heatsink, while low pressure models become unusable when put close to a heatsink, be it push or pull mode. The worst fans for this are the SilenX ones which work fine only in open air, Enermax batwing models (UCCL UCEV UCMA) are very good for pressure but have rounded frame edges, Scythe Slipstreams are similar to Enermax but the best fans I have for this purpose are the stock fans that came with the heatsinks, the Noctua NF-P12 model which is basically the same for noise but can force more air than the others I tried. The only problem with these fans is they ain't PWM capable so I have to put back to work the little converting circuitry I made last year

 

[pm.stacker]

I have ordered two more blue ducts and a third Noctua NH-12P fan to experiment more on this approach for now, the Scythe remains on the exhaust, and since it has a slower speed compared to the Noctuas the PSU gets warm, but next week it'll get solved .
Oh, some little circuits I made to turn any 3-pin fan in a PWM fan