Speak English. Fuck.

If you only want to run 3 GPU's, you can get away with a cheaper board. I'm sure you can get cheaper options from ebay.

Motherboard: ASUS M5A78L-M LX PLUS AM3+ AMD 760G Micro ATX AMD Motherboard 3 PCI-E slots for 60 bucks

Power Supply: I won't fight you against the Seasonic. Many people seem to have their own preferred brand. TBH, if you're mining, make sure it's at least 80PLUS Silver. Try to go for 80PLUS Gold though. Also single rail is a big plus, it means less figuring out load balancing. Your power supply choice meets both of those. I do not believe your system will consume much more than 600 watts with stock volts on the video cards though. I have 4 5870's undervolted and they draw 550 watts on 83% efficient power supply. Anyways, if you don't think you will expand, look into getting a lower capacity power supply, maybe 750 if it saves some money. Also, if you think you'll run out of PCI-E power cables, I find these are amazing. Athena Power Model CABLE-EPCIE1628 16" PCI Express 6-Pin to Dual 8(6+2) Pin Linear Extension Power Converter It splits a 6-pin PCI-E power connector into 2 x 6+2 power connectors.

RAM: You can get away with 2 or 1GB of budget RAM. Dedicated mining on Win7 with 1GB of ram will work fine.

CPU: Overkill. Get a Sempron 130/140/145, save yourself some money and electricity.

HDD: Windows 7 will not install onto a USB flash drive (at least in my experience). You will only need about 15GB to be "safe". You can also look into finding a SATA to SDHC card adapter and install your OS onto an SDHC card. It will save you electricity.
Adapter and 16GB SDHC card $19 for both

It may not be 7 slots, but I'm happy with 6. I'm not about to return it (and the cpu) for a 20% restocking fee, plus it was a big pain in the butt setting it all up. Probably overpaid a little for 6 slots, but the CPU, board, and hard drive only consume about 25 watts at the wall on an 80plus gold PSU, which means better overall mhash/j

Plus I like MSI's board layout. I got an x79 Big Bang XPower II in my main PC. The only nuance is the silly chipset and mosfet heatsinks.

Also, FWIW, the Celeron G440 only consumes 5 watts when idle, and 9 watts under load with linpack. I have not extensively tested the ondie GPU, but hwinfo64 claimed the GPU package was only taking in 0.064 watts when I was getting baseline power consumption with no video cards installed.

Update2: Got a 6th slot working with the assistance of a presence short. #7 proves difficult. I'm hoping it's just a bad riser or bad short, but each 1x slot above a 16x seems to work.
Edit: I put in a ticket with MSI a few days ago, this might be relevant. Here was the response. Very bad english, but the important part is at the end.

Necroedit: old pictures removed.

Update: Got 5 slots working so far without the assistance of a PCI-E presence short. This is with all slots populated with a GPU via a 1x > 1x riser.

Would you do $125 shipped for reference 5870's? I could go for 2, maybe 3.

Well I got it in the mail 2 days ago. Yesterday's time was mostly spent making a wooden frame to mount the motherboard and video cards on as well as a place for the hard drive and power supply to lay. Like my other rigs, the motherboard will be "upside down" (the CPU is closer to the ground than the PCI-E slots. This means the graphics cards themselves are right-side up). I've been having a couple problems with my hard drives not being reliable, but I think I finally got a keeper. Anyways, the 3 slots closest to the CPU are populated so far with 5850's. None of them need the PCI-E presence pin shorted. I'll have to steal some 5870's from one of my dedicated rigs to attempt to populate the remaining slots.

Fun fact: With an 80plus gold PSU, a G440 CPU, 1 2GB stick of Crucial RAM, and 1 500GB 7200RPM hard drive, this only consumes a meager 25 watts of power, verified by a kill-a-watt. Amazing how efficient newer technology is! :O

Optimum memory speed is highly dependant on the actual core speed. I'm working with blinky and chsx3 to find the optimum memory speeds for a cypress XT GPU (Hemlock, or 5970, uses the same GPU). So far I've gotten promising results from blinky's perl script. Basically, I'm brute forcing all of the normal combinations of memory and core speeds in multipels of 1 and 5 respectively. There is no set memory speed that is better than all the rest across ALL core speeds.

Chances are your miner for your 5xxx card is using phatk or phatk2 kernel, 128 worksize, vectors, and bfi_int, and hopefully yo uare using 2.1 SDK (not 2.6/2.7 which comes with the latest drivers. 2.4 and 2.5 is also suspected to be slightly slower). Here is some incomplete, but very GOOD information on what memory speeds you SHOULD be using. I have 4 5970 in 1 rig and was running 150 memory across all the cores. Using this spreadsheet, I was able to increase hashrate by 15 mhash. It's not much, but it WAS an increase. It's now doing exactly 2.7 Ghash with 910 watts, or 2.967 MHash/joule, compared to 2.685 earlier. Note that I can only recommend these speeds if you are using the above settings.

Is that 5 pci-e slots on the foxconn? Know if they all work at the same time?

Your power estimate seems too high. I drew 1040W at the wall with 3 5970 and 2 5870 (all reference) with an 83% efficient PSU. This is about 863 watts. I believe it also did 2700 mhash, or 3.12 mhash/J (assuming 100% efficiency power supply)

Got the 1300W rosewill in the mail today, along with my G440 CPU and MSI Z77A-G45 mainboard. I got hard drives, memory, and vidoe cards laying around, and am in the process of building a third frankenstein. I cant wait!

Edit: I decided to redo some of my rigs while I decide what to do with my HALE90 (it's not in resellable condition, melted modular port and melted molex cable). It's currently powering a 4x5970 rig, consuming 910 watts at the wall and 2700 MHash/sec, or 2.967 Mhash/J.

I had a present in my PM box this morning! The creator is offline for now though, waiting for him to get back on to resolve some bugs.

Sounds like you dont have an appropriate sdk installed.

Bump. I figure I'll use this thread to post any hot buys I find in the future that I don't want to take advantage of.

I received the 5970 a week or so ago and is happily mining away on it.

Still selling?

Still selling?

You mean this? http://www.ebay.com/itm/271020875741

Nope. Not one bit. Static 1.088v all the way, though it is likely higher than 1.088v. Probably in the area of 1.15. I have 2 cards that are stable at around 1000MHz for mining, no way could that be done at 1.088v, even though thats what sensors and BIOS reading says.

lol look at the top card bend.

Up.