reaper asks for 1.5g RAM for each 7950......

Consider HX 850, that's the PSU so far I found has 6 * 6 pins for 3 cards,  I am still digging

http://www.newegg.com/Product/Product.aspx?Item=N82E16813128509
have a look at the mobo, which allows you to put 5 pcie 16, of course you will need pcie extend cable
I remember there is one gigabyte mobo can hold 6 pcie 16 but can't find it.
but the price is definitely cheaper than the asus one.

for psu, go biiiiiiiiiiiiiiiiig, coz cheaper PSU won't give you enough 6+2 pins for video cards, since you choose 7950, each card you will need 2*6-pins
if you plan to have 2 or 3 of 7950, have a look at the HX850 which comes with 6*6pins
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011

my Powercolor 7950 reference can undervolt, but not too much.
otherwise cards will crash.
now I am running all my cards at 1.063v mining LTC

3*7950 each hash at 510, 980/1250 undervolt to 1.063 ---> total 1510Kh/s
when all the water cooling components arrive, I will OC these 3

1*7850 hash at 310

so total 1820 +/- 50

it's hard, so I let it run naked
unless you consider water cool your cards.

try to reduce your intensity parameter 

you can actually use all your cards to mine under the same worker, you can but you don't have to separate them.

here is my miner running totally naked
https://bitcointalk.org/index.php?topic=7216.msg1660185#msg1660185

I tried to put it in a case but the temp will go up 5, so I pulled it out again.

I am living in an apartment and there is no dedicated space for the miner, also it's to noisy with the big 20 inch fan running.

so I drag it to the kitchen in the evening and drag it back to my bed room during the day (without turnning the rig off), and I always stay in the living room, basically it's safe

nice, nice, I finally ordered 3 EK universal GPU water blocks and a Koolance 450 pump for my 7950s, but I guess I will need more rad, one 360 maybe not enough for the summer

should be yes for both LTC and BTC

that happened to me before as well, try to reduce the -I to the threshold that gives you no HW error at all, maybe it's a good idea to start with -I 13,  otherwise all cards are just generating useless hash and waste your electricity power.

BTW, try to lower your voltage, your cards are too hot.

I got this XFX 7850 Core Edition
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150642

with OC of core, it's mining at 310-320Kh/s

interesting, did you try to change -w to 128 or 64? and try to keep the core/memory ratio to about 0.7

Nice rig, I am trying to water cool my miner, but 4 VGA water blocks are really pricey, still thinking 

Are you using 2 * 240 rad in the loop?

assuming it turns out BFL is a scam, so Avalon successfully make itself a monopoly 

Are you running 4 cards all together and each get 330Kh/s

I might be wrong, but if you are mining LTC with 4G of RAM and 4 7870 cards, it's not a good combination.

I personally use 3 powercolor 7950, the max -I is 13 higher than this will product massive HW......so I guess you don't need to bother this parameter

you don't need --thread-concurrency 8192, my cards all mining at 510Kh/s just fine without it.

so I can only conclude that increase your system RAM to 6 or 8G, and see if hashrate increases

I am done with XFX, their cooling fan sucks.
I bought a 7850 and after exactly 30 days, the fan starts to make griding noise.......
never bother to sent it back, coz they will replace it with a refurbished one, now I keep using it and the griding sound seems go away.

the funny part is, their customer support claim that I can change to aftermarket vga cooler as long as I keep the original parts, and restore it in case of RMA
then what's the point to stick two giant "VOID" stickers on the screw.
 

I started mining LTC by using my macbook pro for about 2 days (the difficult was much lower) and the noise really kills me, even I put it on a cooler pad.

Actually it has nothing to do with electricity cost, it's just not worth it plus apple scarifies inside space of its laptops in exchange for a compact size, specially Mac airs,
so heat will kill your laptop quicker.

If you really want to get the fell of mining.....just grab a 7850, it will payoff itself in a year or less.
 

It seems anything can do the mining job won't go cheap.
Anything cheap won't do the mining job, e.g a shovel 

Then temp is nice, I guess you only dig btc?
Coz when I am mining ltc, the "naked" rig stays at 70 with a 20 inch fan blowing....