I recently purchased a cooler master 690 ii advanced (in spite of some warnings on these forums) and I have to agree its not a quiet case. For now I'm just focusing on getting the system up and running without putting too much effort into silencing it so there's no doubt room for improvement but it will be a while before I get around to it all (though I hope to report back).

Right now its running the three stock fans that come with the case (2x140 and 1x120) and the stock fan of my Scythe Mugen 2 cooler. I haven't put a lot of effort into controlling the fan speeds yet but I'm wondering what some reasonable numbers would be. The case fans are running at around 450, 750, and 800 rpms (not sure which is which) while the cpu fan is around 1100 rpm I guess (though these numbers might be mixed up). My core temps are around 30-40 C and my gpu temp is around 30 C so I guess I'm over-cooling this system. For my specs check this thread:

viewtopic.php?f=15&t=62152

The system as it is is noisy. The fans generate a noticeable background whir and the HD is quite noisy when active (unfortunately I could only get hold of the WD black edition though I was planning to get a blue one). I can live with the HD noise but would like to maybe slow down the fans a bit and even disable one. The CM 690 has a front fan, a back fan and a fan on top. Along with the scythe mugen fan that's probably too many. Would it make sense to disable to the fan on the top of the case and slow the others down? What would be reasonable fan speeds (assuming the bios gives me enough control)? What temperatures should I aim for before I worry?

Thanks

As I understand it, you have 2 x 140mm fans running at 1200 rpm. The airflow from these two fans will be substantial and the major source of fan noise. A cheap and simple solution would be to use a Zalman Fanmate 2 on each, and cut the rpm by around 50% to 600 rpm or lower if you can. This on its own will cut most of the noise.

The issue then I think is that you need to minimize the speed of the remainder of the fans at idle, but once the system is under gaming load to have supplementary airflow in addition to the 'background' airflow provided by the two slowed down 140s. A solution adopted by many gamers in this situation is to use a PWM fan chain. The Mugen 2 has the excellent Scythe SY1225SL12LM-P PWM fan, and you could purchase two more of these and the Akasa Akasa AK-CB002 PWM fan splitter cable. This cable takes the PWM signal from the motherboard, and power for all the fans from the PSU. If you use one of the additional fans to replace the existing exhaust fan, and fit the other in one of the positions at the bottom of the case these will give you a chain of three PWM fans. I assume you have the Asus motherboard, in which case you could set the PWM mode to Silent. Under idle, with your case, all the fans on the chain should idle at around 400-500 rpm and under load automatically increase in speed to around 1100 max. The bottom position is suggested because this will give an airflow directed at the graphics card, and will help to minimize the speed of its PWM fan(s).

The best way of testing gaming system cooling setups in my opinion is not to use the somewhat crude and outdated Furmark, but a benchmark such as Unigine Heaven DX11 2.5 which gives a system stress more typical of a game. Even with a PWM fan chain I would expect to see this benchmark, at its highest settings, increase the CPU temp by around 20-25C, and the graphics card temperature by 30-35C. This range of temperatures reflects that both the CPU and the graphics card are going to underclock and undervolt at idle, but will run at maximum speeds and voltages under load. And the CPU may also engage a turbo mode.

There is some scope to reduce the fan speeds on the graphics cards by using MSI Afterburner, which is a fairly universal utility for this purpose and will work with any make of card. It will allow the creation of an improved fan profile for a quieter idle if the fans on the graphics card will go down to 30%, many cards are set to 40% as standard and some of the overclocked ones to 45%. So there is some scope here to trade slighter higher idle temps for less graphics card fan noise.

Thanks for the informative reply lodestar. Strange as it may sound I'm not very likely to be playing games with this system. I intend it more as a workstation for photo-editing and mathematica. These will likely strain the cpu more than the graphics card (unless they start using cuda). Unfortunately the graphics card is overclocked (msi gtx 560 twin frozr ii/OC) and I would be happy to underclock it and set the fan speeds lower but I'm using linux so I'm not sure if there's an equivalent utility to the one you mentioned.

I have used the asus bios to set the fans to the silent profile but they're running at 450, 750, 800 and 1100 rpms. I'm actually not sure which one is running at 1100. I seem to remember the bios reporting that the cpu fan (on the scythe mugen) was running that high but that's strange since I would imagine its the fan on the PWR connector that is (the p8p67 has 4 fan connectors, three which can be controlled from the bios and one "PWR" one which I guess cannot). I think the bios lets me control the speed of these fans by setting min/max speeds and temps. I am going to experiment a bit with this but was wondering what good ballpark numbers are for quiet fans and too hot cpus (to get some bounds). Is a lower fan speed of 200-400 rpms relatively inaudible and is it not dangerously low?

Another issue is that the way things are setup the scythe mugen fan is basically an inch away from the rear exhaust fan. I'm not really sure I can even put it anywhere else but is this maybe a bad idea?

Hi,

It might not be a bad idea to post some pics. The Mugen fan should be mounted on the front of the cooler(next to the RAM) and not near the exhaust fan. Typically when setting Asus BIOS to silent this fan should spin at 250-450 RPM.
It is my experience that some of the fan headers on the Asus motherboard cannot be BIOS controlled. Couple that with a fixed 1100 speed that is common for Coolermaster 120mm case fans @12V and i'm betting its.

To help you get an idea of what is going on acoustically you'll need to stop the fans and activate them one at a time. This is the only fail safe way to know what is causing noise in your system. Most fans become near inaudible under 800 RPM, and just about silent @ 500-600 RPM. I think you should try and get all fans to that speed. If you are not gaming you can remove 1 or even 2 of the case fans and possibly consider swapping your 560 for a cheaper low power/low heat/passive card. I'd remove the top fan first.

I use a CM 690 on one of my home systems and I've tried just about any/all fan position combinations of 120+140mm fans. What worked best for me in terms of cooling was 2 front intake 120mm fans and a single 120mm exhaust fan. Front fans are spinning at about 600 RPM (using a Noctua ULNA) and the back is the stock 120mm @ 1100 RPM. The 690 and 690II are hard to quiet because of thin side panels and poor HDD mounting causing the entire case to vibrate and resonate.

I don't think a WD caviar blue would have made much of a difference in sound. If anything you should try Samsung F3 HDDs.

Thanks for the useful reply, ame. Actually I have to say the system is not very noisy. Its almost inaudiable once there's background noise but if the room is very silent you definitely here it. I'm going to disable the top-fan which is running at 1100 rpms and see if that helps. Unfortunately the p8p67 bios only lets you slow the CPU down to 20% (240 rpms - this is actually fine) and the case fans to 60% (720 rpm). From what you say though this should be ok so maybe just disabling the full power fan will be enough. Otherwise I'll look at getting some fan controllers. I'll post some pics once I have some time to muck about in the case.

As for the mugen fan, I can't put it on the ram side of the CPU because the cooler itself is almost flush against one of the (oversized corsair vengeance) ram sticks. I could move the sticks and there _might_ be enough space but this would only work if I don't ever add more ram. Can I put the fan on top/bottom of the cooler (I'm not even sure there's a mount for it but will check)?