Hey all! Thanks for the help with what is probably the most posted and contested question: What should I buy?
Right now i have a CHENMING CMUI-601AECB-U case, which is large but unwieldy and only supports 80mm fans. I run it mostly open case with the case fans off (the existing fans are LOUD), but between the GPU and CPU screaming at me, I really want to enclose and cool it properly. I just bought a pile of low speed fans to try to keep it cool and quiet, but haven't tested them yet. Needless to say, I am always looking for a new case. Newegg just posted a large drop in price of the Antec 280 ($120 minus a $20 mail in rebate minus $10 promo code), so I started looking at that and comparable cases as well. I have:

CORSAIR CMPSU-750TX PSU
MSI 870A-G54 AM3 Mobo
Western Digital Caviar Black WD1001FALS 1TB HDD
G.SKILL Ripjaws F3-12800CL9D-4GBRL x2 RAM
AMD Phenom II X6 1090T CPU
Sapphire 5850 GPU

Needless to say, not quiet or low power, but I don't need/want my computer screaming at me while I try to use it. I use it primarily for large computational jobs (I do molecular dynamics simulations) as well as gaming, so I need airflow, etc, to keep temps down and component lifetimes high.

Right, so, to the point: Want a case in the $100±25 range that will support this kind of head dissipation load while staying quiet, with the potential to upgrade the GPU when the nice, sweet, 8000 series comes out and isn't a total disappointment like the 6000 series was. I've been looking between the Antec 280 and the Fractal R3, with the idea of completely loading them up with quieter, slower fans, like the Scythe SY1225SL12L to keep air moving. Thanks for all the help!

The Antec P280 is a fine choice. Even with stock fans (set on low), you'd probably be perfectly happy... at least for a while: Quiet can be addictive... and quieting a computer can become a serious addiction.

The PSU could be quieter. IIRC, that Corsair is made by Channel Well, and it isn't anything like the Seasonic-made ones -- considerably noisier even at min load, default fan speed. Cheap solution is to swap out the fan, if you are a DIYer. Replacing it with a PSU from SPCR's A-list will get you a higher efficiency, quieter unit.

The WD Black isn't quiet either, though, and it might even be loud enough to make the PSU noise a non-issue -- ie, even if the PSU was quieter, the HDD might be loud enough to make no (or little) difference to the total sound. It probably needs suspending & enclosing to be really quiet, depends on how far you want to go. Maybe the rubber grommets in the P280 case (and other cases) might be enough for you.

Another option is to move to an SSD for your OS & programs -- a good 120gb drive is pretty cheap these days & big enough for just about anyone. Move the WD to an external eSATA box, use long cables to distance it from you, and use it only for data, you could even keep it turned off and turn it on only when you need to access it.

Hopefully your video card is quiet at low load and its fan doesn't yoyo in speed with load. If so, consider a heatsink replacement.

Finally, the CPU is really the easiest thing to cool quietly these days -- if you have a big cooler with a big fan. If you are using a stock HSF, again, I refer you to the recommended products for a replacement -- http://www.silentpcreview.com/section5.html

Thanks for the reply Mike! And the great welcome to the community! Yea, the PSU is a noisy beast when I am drawing a lot of power. I am definitely looking at the gold and platinum rated PSU's recommended here to drop power draw, temps, noise, etc. Seems like it's a win all around. The Black HDD wasn't chosen for quietness, alas, but speed, it was for a while one of the fastest HDDs on the market. This was more for the simulations than the games; it helps both, but the simulations really need the space and low latency. I really want to avoid overloading the CPU with a heatsink, I've been looking at a Big Shuriken 2 Rev. B which keeps the weight down and has some blow-down to the VRMs, though it does make it harder to get the CPU heat out of the case as its now spread all over.

I've got a small PC which I built to be quite quiet thanks almost entirely to this site. Lots of wonderful reviews and info and a deep deep forum with great users! I would call the PC an "HTPC" but it's in the basement, serving everything across the network. Having it downstairs and through several walls makes it really quiet! I would love to get a big RAID 5 array for this guy but right now its JBOD.

FYI, I have some used Smart Drive 2002 HDD silencers; one would certainly help quiet your HDD. Not cheap, but very good. Email me if you're interested -- mikec @ you know where.

I was ready to click this post closed when I saw MikeC had already taken care of the answer, but then I laid my eyes on this wording. That setup is in no way "a lot of power draw". This review should explain why: Six Cores from AMD: AMD Phenom II X6 1090T Black Edition and Phenom II X6 1055T CPU Review (X-bit Labs).

In short, they used the same 1090T CPU, an enthusiast mobo with 890GX, a Radeon HD 5870 and a VelociRaptor (like HDDs make a big dent) for the test, and the system ate up no more than 164 W at 100 % load. Assuming a minimum efficiency of 80 % (80 Plus PSUs can do at least this much easy), that's 205 W "from the wall", as in rated wattage.

Go for a low wattage, quality PSU from the SPCR list. It's not a big investment, will erase some of the noise and last you a long time (5 year warranties not uncommon, can attest to longevity of good PSUs).

That's about right, the CPU should only ever pull 125W and the Mobo, HDD, etc, usually pull no more than 50W all together. But thats at steady state - when running. And without using the GPU at all. When booting, the system draws a lot more power to bring everything up. Though newer motherboards spread it out a bit to reduce the inrush current, HDDs especially draw 2-3x their rated power to get the platters spinning, etc. The GPU would be the kicker for me, as that at 100% (which mine does get to), has a TDP of ~150W. And I don't want to push myself out of the dual GPU market. Another two teraflops of processing power can go a long long long way. Especially when my CPU is "only" capable of 0.05 teraflops. Max draw is still around 425W, plus a bit of overhead for startup, means I could go down to 500W-550W. I am looking at the LZP-550 from Kingwin, has pretty good reviews and platinum certification. Thanks for the posts and the links!

500 W is usually where people settle, enough for most anything, especially so single GPU gaming rigs. I consider it "low" in the current climate of kilowatt PSUs, certainly lower than 750 W. That Kingwin unit looks good, especially based on the SPCR review. Good luck with the build!

As a side note, the HDD spinup issue seems like a bad memory from the past. Last time I came across it was when Intel's first Core 2 processors were out, and that was with outdated hardware.