It has no voltage control. I can't even see the current voltage in MSI afterburner. It can currently get up to 780mhz without errors in OCCT gpu test. Is there anyway to increase the voltage on this card without having to hardware mod it? Temps are not a problem.

When using a PCI express x1 for mining, does the GPU get enough power? GPUs are designed to get 75 watts from the motherboard but are the x1 slots capable of supplying the power? Also, does the hash rate go down when using x1 slots?

Really? it seemed kind of reasonable to me.
4 X 5850 $580
cpu $30
ram $16
psu $200
mobo $60
hdd $20
dvd drive $20
tax $25
shipping $15
PCIE extensions X 4 $20
aluminum and screws not sure, probably $20
That calculator doesn't account for a difficulty increase though

if i payed $1000 for a 1.3 ghash/s system, i could pay that off in about in a little over half a year at this difficulty. ($0.14/kwh)
I'm not familiar with how difficulty increases (how often, how much) so how long would it take to payoff the system if the BTC price remained the same but difficulty increased as it is now?