New Mining Computer, What combo should I use ?

[CoolIT]

We are considering making 3 of the following group. Which would you recommend ?
Also, some machines doing litecoins.

Let me know if I did any mistakes. Thanks.

3x Saphire 7950's
Raidmax 1200W psu
ASrock 990FX Extreme3
No lifters needed with the above motherboard
Generic Kingston Ram, about 4 gigs
AMD Sempron 145 2.8Ghz


Or


3x Saphire 7950's
Raidmax 1200W psu
ASUS P8B75-V LGA 1155 Intel B75
3x HOTER PCI-E Extension Cable 1X To 16X Riser Card Adapter (Would this work ?) http://www.amazon.com/HOTER-PCI-E-Extension-Cable-Adapter/dp/B0057M1ZLE
Generic Kingston Ram, about 4 gigs
Intel Celeron G1610 Ivy Bridge 2.6GHz LGA 1155 55W Dual-Core Desktop Processor BX80637G1610


Thank you for your input.

-Dan

[miningdude]

If you only want to run 3 cards, the first option could work. However, since you're already investing in a motherboard, PSU, etc why not add a 4th card using the risers? Something like this build guide shows:
http://www.coinminingrigs.com/quad-7970-mining-rig/

Also, keep in mind if you are building a GPU mining rig, you are speculating that whichever crypto-currency you are mining (WorldCoin, LiteCoin, etc) will rise in value in the future as the profit margins are pretty slim at the moment, once you've paid your electric bill.

[CoolIT]

We rent in an industrial building, electricity cost included  

I am already running 2 unimpressive machines built out of used parts.
My friend got interested in making something a little more interesting.

[HellDiverUK]

I'd go the 990FX every time.  I had problems with the lower end Intel chipsets.  My main mining rig is an Intel based machine, an Asus P8B WS (C206 chipset) with 3x7950 and an i3-3225.  My other one is on an Asus SABERTOOTH 990FX board, running an FX-8320, and a pair of 6970.   It's got a beefier CPU as it's also my game/workstation.

[systic]

Id biuld 2 of the secodn with 4 cards each