well currently each of my rigs with 6x r9 290's

   Temp    Load      Rate            Accept/Invalid          GPU Family  Fan%  (rpm)    Core      Memory   
   75c   100% 160 Kh/s   11740 / 865   6.86%   290 Series   65% (3738) 940 Mhz 1250 Mhz
Average Card speck,  lowest reject rig is around 4%
Before I upped TC from 32765 to 42000 I was running I 13 ( 150 watts / GPU)
Now back to I 18 and double my kh/s with around 4% increase in rejects
about 200 watts / GPU  out off the  300+ watts when using I 20

each rig is getting 980 Kh/s 150.347 UTC coins / Day

(I was getting 300 coins yesterday with core of 900 mhz !!! I bumped core speed up because of extra miners  )

Pool Hash Rate    29.192 MH/s
Pool Efficiency    98.31%
Current Active Workers    86
Current Difficulty    6.50879778
Est. Next Difficulty    0 (Change in 0 Blocks)
Est. Avg. Time per Round (Network)    zero seconds
Est. Avg. Time per Round (Pool)    15 minutes 59 seconds
Est. Shares this Round    26660 (done: 438.36%)
Next Network Block    94528    (Current: 94527)
Last Block Found    94382
Time Since Last Block    1 hour 16 minutes 35 seconds    

*edit*

really need to get flashing test rig was impressive
https://litecointalk.org/index.php?topic=12830.msg121827#msg121827

flashed with 1.1V bios and can now run I 20 again
only dropped about 10% power usage

2x cards 370 watts @ 940 core I 20 .. might try bumping the core up to 1ghz thats normally 320 watts per card ...

how ever I am unsure what total power drain is I am only measuring from 6/8 pin power plugs not taking into consideration of PCI-e slot drain .. might rectify that now before I blow another 500 watt PSU


*edit*
PC booting up is 120~150watts
PC mining with 2x R9 290's bios modded 1.1V is 520 watts
also noticing with bios mod my WU is higher then my hash rate !!!

when I first benched Twin R9's I was near 800 watts ( but it was a different Mobo and 1 ghz)

now that I know hardly any pci-e drain I'll bump the core up for a quick spin
oem cooling so for long term use trying to keep everything around 70 deg .. last time I was near 100 deg in seconds and vynal floor started melting,  test bench aka floor

*edit*

manually set fan 85%
1ghz core
twin R9 290 mobo mining under 600 watts
very impressed with modded bios about 50 watts difference from 900 - 1000 core
and drum roll .. temp low 73's room temp 34 - 37 ( HDD temps of file server )

how ever not really any change in khs / WU I gained a whole 1% with over 10% increase in watts

soo maybe back to my 900 mhz sweet spot any how

if it wasn't E RAM I would be OC'ing em