P183: Top Fan Configuration

[Sunfox]

I'm nearly done building my new system housed in the P183. The last system I built 4 years ago is in a P180. Although I don't yet have the SSD I want (it arrives Monday) for the past week and a half I've had my system built simply for stress testing purposes, and to mess about with benchmarks and such before I do the final OS install.

The upper compartment is cooled by 2 Slipstream 1200RPM fans (actually 1300RPM at full speed), one blowing in the front and one out the back. Both are controlled by the motherboard, speed based on the voltage regulator temperature. The CPU is an i7-990X 6-core, cooled by the Venomous-X heatsink with 2 Slipstream 1300 RPM PWM fans (actually 1400 RPM) in a push-pull configuration, controlled by the motherboard's CPU header. The lower compartment has a CP-1000 power supply, 4 HDDs and a Slipstream 800RPM fan blowing in the front, static speed stepped down to ~500 RPM.

At idle, the case fans run at 800 RPM, and the CPU fans are at 650 RPM. I've seen the CPU at 29 degrees idling. Since the heatsink is so friggin' awesome, I had to spend a while tweaking the trigger temperatures and ramping, since with stock settings the heatsink was perfectly capable of keeping the CPU cool at only 440 RPM, but the voltage regulator needed more cooling, so the motherboard was cranking up the case fans to 1300 RPM - unacceptable.

Now, after adjustment, multi-hour stress testing (LinX and Prime95) tops the CPU out at 950 RPM and 59-62 degrees, and the case fans at about 1100 RPM. The system is still VERY quiet and all you can really hear is a bit of air moving. When the stress test is ended, everything slows down immediately, and returns to idle speeds within 20 seconds. By far the most powerful and silent air-cooled system I've ever built.

Through all of this, I haven't had a top blowhole fan, because while building I read that the Slipstreams shouldn't be used horizontally. I've ordered new S-Flex models for this position, but based on my stress testing I'm uncertain whether I should even bother installing one - and if I do, whether it should blow in or out. The fan would be controlled again by the motherboard, but this time tied to the IOH temperature sensor, which I've never seen vary by more than 3 degrees, so it would be pretty much set to a static speed (except in case of something overheating for whatever reason, in which case the m/b will turn it on full).

Out, you say? Well, I don't know about that. First, with the cooling as it is now I've determined that the top hole is being used as an intake - a piece of tissue paper will stay stuck to the grill. Second, on my last two P180 systems, I found that my CPU/motherboard would stay around 3 degrees cooler with the top fan blowing inwards, versus outwards.

I've had about 6 years of P180's configured this way, with no issues. My current P180 system (QX6700 4-core CPU) has had the top fan blowing in for over 4 years, and dust hasn't been an issue (the case is under a table, so there's not much chance of things falling or drifting in).

Block off the hole? I actually experimented with that tonight, and things did not fare well. Without the additional air, the CPU fan was 100 RPM faster, and the case fans eventually topped out at 1300 RPM as the voltage regulator was getting warm. As soon as I unblocked the hole, all temperatures came down... the graphs were quite decisive that it should be left open.

I was going to experiment with the top fan blowing inwards again, to see if it helps cool the voltage regulator... or if all it does is keep the CPU cooler (and frankly I don't need the CPU any cooler than it is - I've already lowered the temperature threshold by 18 degrees to get its fans to do something under load!)

Any advice from folks who have been where I am?

[fumino]

what are you using to control fanspeed?

speedfan would allow you to control the fan based off of any temperature reading... if your board supports it.

[Sunfox]

Fan speed isn't really an issue at this point. But for now I'm using the motherboard's utilities, which are quite unobtrusive. Haven't tried Speedfan, but the way thing are now there's CPU (CPU temp obviously), Front, Back (both use voltage regulator temp) and Aux (uses IOH temp, I was going to use this for the top fan). There's also an ambient sensor tied into an overheat setting.

[Sunfox]

An update. Got my fans today, stuck an S-Flex 1200RPM at the top blowing in at 500 RPM. Now the voltage regulator is staying 6 degrees cooler, and as a result the front/rear case fans are able to run 200 RPM slower (850-950 RPM) at the same settings, making the whole thing quieter and cooler than before.

I'm very, very happy - this thing is incredibly quiet versus any quiet system I've built before, especially under full load with 6 cores @ 3.73GHz.

Only thing I wish is that the Sapphire HD 6870 Vapor-X was somewhat quieter when IT'S under load (although it is utterly silent at idle), but I guess I have to live with what's available.

[quest_for_silence]

Only thing I wish is that the Sapphire HD 6870 Vapor-X was somewhat quieter when IT'S under load (although it is utterly silent at idle), but I guess I have to live with what's available.

You might try to adjust fan curve with something like Rivatuner or Afterburner, I guess (or even give a look to newest SpeedFan release, in order to know whether or not currently it's able to control the ATI's fan with reference to GPU temp).