Some very good advice from DeltaForce especially since it comes from an experienced gamer concerned about SPCR level quiet.
My own interest is to push a little harder toward what would be considered by the enthusiast/gaming/modding/overclocking community including forums, reviewers and boutique system integraters as "high-end". The tendency in this community is to want and show interest in the latest high-performance technology.
There is now a widespread enthusiasm for quiet in this community, but it generally is unwilling to compromise as much as the SPCR community. This is nowhere more apparant than with the graphics card. I was having a conversation with 3 avid gamers yesterday and was mildly ridiculed for not wanting SLI.
There are a number a perfectly good mid-range choices for building a quiet gaming pc with very good gaming performance especially with a mid-range choice in monitors. For a quiet PC enthusiast who wants to do some gaming, these choices are eminently sensible. And even these choices usually involve compromise.
My own perhaps foolhardy project is motivated in part by going to boutique pc vendor sites, drooling over the high-end oft-overpriced configurations and asking 2 questions: could I build that myself for less? And, could I make that quieter? The answer is yes to both questions, the real issue is "how much quieter, how much less expensive?".
Case in point: Velocity Micro's Signature Edition Gaming PC, starting at $7300.00! http://www.velocitymicro.com/wizard.php?iid=75
Take a close look. Welcome to the world of high-end gaming systems! When I called to ask a number of questions, I asked about noise. The rep. put me on hold to consult with the tech who builds these. The answer was 50-52 dB on full load, 35-40dB when idling. After further discussion it became clear that no attempt was made to use quiet fans.
Look at the "Raidstorm" hard drive cofiguration: a raid host controller card and 4 150gb raptors in raid 0 array! Much could be asked here, but to be brief, I can buy an Areca Arc 1210 PCI Raid Controller (the one Velocity uses) for $310, and 4 raptors for $800 after rebates. I'm going to have to spend $250.00 more to put the drives in SmartDrive 2002 hdd enclosures to do the best I can to keep them quiet without heating them up, and I'm going to have to use 5.25 drivebays AND leave space btw them (space can be used for dvd, controllers, etc).
Clearly this is an extreme example. My point is that if I were to go through the entire configuration and add quieting where helpful, I could build this system for $1500 less and lower both idle and load noise by 10dB. If I simply change cpu and gpu choices to 1 performance level lower, I can save over $1,000 more and reduce heat. And with just a few more low-price modifications for quiet, The noise level could easily be reduced a few decibles more. The biggest challenge, again, is gpu heat/noise.But if you drop the sli, you have again reduced heat and noise, you have some room to innovate a better noise/cooling solution, you still have 1 truly high-end card, and you've just saved another few hundred $.