During the past two-three weeks I've been rebuilding my computers in hope that I can achieve a quiter overall operation. Prior to the overhaul I had two computers, my main rig with four harddrives and a backup 24/7 rig. The backup rig was a heavily underclocked/undervolted mobile athlon with a fairly bizarre cooling system, but it was relatively quiet and it was standing behind the wall in a closet which made it nearly inaudible, although I had to modify it too because it was getting louder. The main rig was fairly quiet with the loudest thing being 4 hard drives in it. It was those hard drives that pushed me over the edge prompting me to rebuild my systems. For that purpose I've built another computer to serve as a fileserver and moved it into a closet leaving only one hard drive in my main system.
I plan to do a "showcase" of all three. This is the first in the series (and conincidentally the most boring) which describes the fileserver.
As I said this is the most boring part since it utilizes standard P180 with minimum mods. However there are several points that I think spcr members might find usefull.
Intel Mobile Celeron 1.8GHz + Zalman 7000
4 HDDs from various manufacturers
Enermax Noisetaker EG475AX-VE(W) SFMA
The lower chamber
There are four harddrives mounted in the lower chamber with standard P180 gourmets. The powersupply is not enough to cool all of those alone, so I had to add a fan in the chamber to keep them cool. The fan is Yate Loon D12-SL connected via resistor to a motherboard header. It spins at about 950RPMs, that's slightly more than I would have wanted it to, but given that the server will operate without any supervision in a closet with presumably higher ambient temps, it's probably for the best. Since the computer is going to be in the closet most likely I won't even hear the difference.
The power supply is first revision of Enermax Noisetaker with active PFC. Cost me quite a bit back in the day both in time and money (had to RMA to newegg twice). It's a good PSU which is regulated by internal thermistor and also has a knob outside for manual adjustment. Under heavy load it tends to ramp up unnecessarily at which point globe fans start to click like mad, but at minimum RPMs it's extremely quiet. Fortunately all the HDDs do not put enough load for it to ramp up and I have set the control knob to its minimum so the PSU itself is pretty much inaudible. Like most of the dual fan and 120mm PSUs it exhausts some of the hot air back into the case, but Yate Loon fan in the lower chamber is strong enough to push it all in the proper direction. Actually I think I could have run the PSU without fans at all, Yate Loon pushes more than enough air, however I did not attempt it.
As you can also notice there is sort of a duct at the back of the PSU. I added the duct because I thought computer exhaust will be facing another computer intake so I wanted to route the air up. I ended up positioning my PC the other way though. I also thought it would reduce the noise, but I'm not really sure if it did. It may in fact making it louder.
Another thing that you may notice in the very last pic is that my computer is standing on MDF shelf. This is done to lower HDD temperatures. I have carpet floors and the computer "sinks" into the carpet blocking the bottom air intake of P180. The rubber feet are not high enough to elevate the case above the carpet. This seemingly simple thing have lowered temperatures by 2-3 degrees celsius across all of my hard drives. It may not look pretty, but if you have carpet floors it my be worth doing it.
The upper chamber
The heart of the fileserver is a microATX motherboard from AOpen 865GM-IL. I chose this motherboard because it's an all in one motherboard with Gigabit Lan, integrated audio/video and two SATA ports. I would have liked more SATA ports, but pretty much all socket 478 motherboards have only 2 SATA ports and those that have more are positioned for higher end segment so they usually don't have integrated video. So as you can see the upper chamber is pretty minimalistic, there is only motherboard, CPU and memory (I took out the optical drive after initial install since I don't expect to need it, it takes space and I could use it somewhere else).
The CPU is mobile P4 Celeron 1.8GHz. These CPUs are very underrated these days. They run very cool - this particular version is rated at 35W, it doesn't take anything at all to cool them, they are compatible with most (check the list though) socket 478 motherboard as long as you bend AE1 pin and the best thing they are dirt cheap. I snatched one from ebay for $12, quite a bargain compared to $70-90 mobile athlon or entry level sempron. Of course, the performance is somewhat of a letdown, but these CPUs are ideal for fileserver or a light load HTPC. It will play your mp3's and even regular sized H264 videos just fine. Although, complicated soft sub effects and hi-def H264 videos will push it over the edge. These are supposed to overclock very well as well, some people reported taking them as high as 2.6-3GHz, which would definitely improve performance, but I didn't attempt it as I don't really need it.
The CPU is cooled by a Zalman 7000 CU heatsink with fan taken off. Since Mobile Celerons come without a heatspreader, the heatsink actually wobbles around the axis a bit, but it stays secure. There is only one fan in the upper chamber - Antec TriCool on low. Without the duct (of which I will talk later) the CPU idled at about 45 degrees celsius. Not bad for a heatsink not really designed for passive operation and no direct airflow around it. Like I said, these CPUs run very very cool.
Now the fan. Unfortunately P180 does not provide a way to softmount the upper fan so I had to make one myself. Someone at SPCR gave me idea so I drilled additional two holes in the top cover and mounted the fan on elastic strings (available at your local wallmart for <$1). This has made a big difference in vibrations which were cut probably in half. Unfortunately I think I overtightened the strings a bit because I can still feel the top vibrating a bit.
The duct was not really necessary but I wanted to have some headroom in case of hot weather or if I would be doing something CPU intensive. The duct is made of simple poster paper, it's fairly thin which allows me for greater flexibility as opposed to plexiglass/plastic ducts. And it's also much easier to work on. I made the duct so that it would cover memory as well, although I don't know how much it helped. The duct is actually kind of loose, in a sense that I didn't take an effort to make sure it completely matches cpu heatsink profile, in fact heatsink is probably twice less than the total intake area of the duct. Even with such loose duct the CPU is idling at about 33-35 degrees celsius, that's about 10 degrees lower than without a duct, so I think that's an excellent result.
The cables are a mess, but that's the original first revision of noisetaker for you. It has very stiff clear plastic cabling so any cable management is pretty much impossible. The second revision of noisetaker doesn't have this awful plastic and supposedly has quiter fans which don't click as much. Nevertheless, concerning the cabling, that's not really a problem since air impendance is directly proportional to the airflow and TriCool on low provides very little airflow, just enough to cool everything efficiently.
The pc is located in the closet behind the wall. I could get a video cable extension and a wireless keyboard/mouse combo, but I already have too many mice on my table and since it's a file server and I don't use it for anything else I just let it be like this. I turn it on using WOL utility and I shut it down using shutdown command. The drives are mapped using batch scripts. So as you can see I don't really need a monitor connected to it, I can do everything over the net. In the worst case I can always remote in if something is wrong.
One interesting fact that I forgot and re-discovered in the process of building fileserver is that most of the hard drive noise is actually coming from the PSU vents in the case and PSU itself. So if you could seal those you could cut down the noise somewhat, as long as it doesn't hurt your hard drive temperatures of course. I couldn't do that in my fileserver so I rotated the case 180 degrees so that the rear of the case now faces the wall now, the noise decrease was quite substantial.
Anyway. Sound wise two biggest offenders are still hard drive (is that really surprising?) and top fan. The top antec fan is actually quite quiet, but the air turbulence when the air hits the upper grill is quite noticable when the case was standing besides the table. Putting computer in the closet made big difference. The turbulence noise of the fan is completely gone, and just about the only thing I hear is the idle noise from the hard drives. I don't hear the whole spectrum, only the higher frequencies. Kind of annoying, but this is the best I can do without moving computer to another room and I can't do that right now.