I'm not sure which Silent Hardware forum fits this best but since I'm building this around the CPU I chose the CPU Cooling forum.

I'm building a new rig based on the i7-3770k processor despite the surprising heat issue. I'll be overclocking to somewhere between 4.0 and 4.5 GHz. I'll decide actual speed based on power consumption (mainly) and cooling noise (secondarily). From what I've read on your forums and elsewhere this is reasonable

The rig will have three major uses and I would like advice on making it reasonably silent.

1) Massive data storage using CrashPlan for my own computers and those of friends and family. This will involve four to eight drives of 2+ TB capacity each. They will probably be "green" drives, though I've had issues with them on the computer I'm replacing. To receive all the backup data I'll leave the computer on 24/7.

2) Gaming. I'm not an extreme gamer, but I'll be running such titles as L4D2 (Left For Dead Two) and will soon start playing Skyrim. Because I've been quite satisfied with my fairly old ATI Sapphire Radeon HD4870 I'm curious to see if I can be happy for awhile with the CPU's HD 4000... But I'm not here for GPU advice. I'll deal with that later, whenever I decide I need something better.

3) Folding At Home. Because my CrashPlan backup goal requires the computer to be on 24/7 but hardly uses the CPU at all I've decided to make this a folding rig as well. That's why I'm going with the i7-3770k instead of a i5-2500k: Paying a little extra for much more benefit to FAH. (The 3770k is not as big an improvement as I'd hoped but after days of digging I'm satisfied that it's still worth it to me.) Folding is also why I'm overclocking, which I've never botherd with before.

So when it comes to noise, there are three issues:
1) A lot of spinning hard drives.
2) I *might* eventually add a strong, efficient GPU also doing 24/7 folding and while I'd consider noise in the selection my first criterion would be folding PPD/watt.
3) A moderately overclocked i7-3770k running constantly at full load.

There's only so much that can be done to silence such a beast. With all those drives I doubt it makes sense to invest in high-end solutions such as water cooling, but I could be wrong.

I'm planning to re-use my case: Thermaltake Xaser-III. I usually run it with the side panel off, which helps keep things cool (I use less that half of its fans) but, of course, eliminates any noise dampening of the case. A new case with better acoustics is not out of the question as long as it has lots of room for drives.

About 8 months out of the year my house is at 66 degrees Fahrenheit. I live in International Falls, MN. That's a big advantage. My computer is on the sunny side of the house, but it'd be interesting to run a heat pump out the window during winter!

One exotic solution I'm wondering about it putting the computer in a different room from the office where I'll use it. If I stick it in the basement and run 15 feet of cable for everything that needs it (USB, video) then not only is the noise no longer an issue but the computer would be in a colder room.

Setting that idea aside I'd appreciate your input on realistic expectations and strategies for minimizing the noise given the limits.

Thanks in advance.

Before you invest in a new machine specifically to run FAH, I would recommend that you find a biochemist and ask them about it. I did, and found out that there is no evidence that FAH provides any benefit to the scientific community or to mankind. FAH does little but create a lot of greenhouse gases and uses scarce energy resources. Keep in mind that I am not a radical environmentalist, just someone who asked around and got some surprising answers. You may not know anyone who is a biochemist, but if you ask your friends, maybe somebody else will.

As you don't need all those HDDs for your new computer specifically, use an older computer for the drives (or a separate low power system in the basement, and your new computer regular usage and gaming.

If not, put it in the basement.

Personally I'm not interested in having computers visible, just like I'm not interested in looking at a circuit breaker panel or a water pump every day.
While not being totally comparable, all three gives me something I need and want, but that doesn't mean that all involved parts must be visible.

Try to put 10 HDDs as far away from you as possible. I'd recommend NAS storage system or 2nd computer specialized for HDDs storage ...... And Use Gbit Ethernet to reach HDDs from main computer. It's next to impossible to silence 10 HDDs by SPCR standard.