That is fine if you use a single psu. ground is ground is ground. makes no odds, and the slots are spec'd high enough on most mbs to happily allow 75 watts grounded into the socket without issues.

However, my situation is a little different:
I use a 250 watt seasonic to power the motherboard and pci-e slots. the psu has 22amps on the 12v.
I use a 750 watt seasonic psu to power the cards.
In my 4 slot motherboards (4 x 16)
Whith these motherboards I use a slightly higher spec psu (again a seasonic,14a and 15a over two rails)
I am using underclocked semperons
A very small ubuntu install (copied from bamt)


Now no matter what psu I use for the motherboard, slot 4 never gets enough juice if all 4 slots are full. (hashrate is normally rocksold 492.1) add a 4th card in slot 2 (0-3) this now hashes full speed and the 4th card jumps between 390 and 441.  So I need a powered riser.  But I need to connect the grounds up on the riser, I cannot risk the 750 watt psu grounding into the 250.

Do the 12v and 3v have different grounds? (there are 3 ground on the front notch) is each ground for something else?  I guess it wont take too long to workout, an inline multimeter should do the trick. I only have two old cards though, still hopefully it wont blow the card.

Does this sound reasonable? do you know anyone who has a schematic for a card with ground connected on the riser. in the pic on cablesaurus it looks like B4 and or B7 leaving out A4. although B4 and A4 makes slightly more sense, but this is just guesswork.  am I trying to fix an nonproblem (letting the card ground from teh 750 into the 250 - every fibre of my being says no)

cheers

steve

Gaming... ?

I was strictly speaking about mining issues. What is difficult to tune?
There are two major limitations (for 7XXX): You cannot alter the voltage or set memory clock more than 150 Mhz lower compared with the GPU clock. (both issues can be fixed with a BIOS flash, although the 7xxx bios editing is not quite straightforward)
Other than that you can tune pretty much everything else I can think of.

Back to Windows, so I read about Windows 8 being able to work with 5 7XXX cards using 13.1.
Can you try that?

Hey guys quick question, i'm using the xfx 7970 double d edition. stock 925/1375

My question, from doing my research online it appears xfx no longer use the reference pcb in these cards, cost saving, so the pcb isn't AMD any more. Would it be safe to flash the bios mentioned in this thread?

I'm struggling to get 550kh/s out of it at 1025/1375

No need to TeamViewer session this.  Here is my example config for a 7970 and two 5830's for mining scrypt based alt-coins.  This is on the verge of stability.  You should be able to gather enough from this to get your own config going.  Read the README's in cgminer documentation.  Look at every variable.  I have this really tweaked, so you may not necessarily want some of the values I have below such as fan speeds, temp target, etc.

Some pictures for help:

The A side is the back side of the card (solder side) with the two 12V pins and the presence (PRSNT1#) pin.

http://www.xbitlabs.com/images/video/geforce6600gt-oc/power_back.jpg



The B side is the front side of the card (with the bulk of the components) with the three 12V pins in a row.

http://www.xbitlabs.com/images/video/geforce6600gt-oc/power_front.jpg


Thanks for the guide BTW.

I hear reviews saying that the Ati control panel is bugged with lucid logix virtu mvp software but if you use nvidia you can access its control panel fine.  no reviews i have found mention losing hardware monitoring..

I currently have the whole virtu software off mode, plugged into the ati card and monitoring temps now fine its just i want to use the onboard igpu that my intel cpu has as it plays games decent, surfs web everything smooth while i can crank 13 intensity on my ati card mining full blast ahead..

im sure we can get it working but have to try different bios configs with primary adaptor, multimonitor option in bios etc.   

i dont use a dummy plug no.  maybie ill try that and see if i can gain my monitoring of the card while usin igpu too.

Yea, get rid of lucid logix, you don't need it. Make sure UEFI is set for the intels IGP. You need a dummy plug for the AMD card. Monitor plugged into the IGP port.

In my thread above, I was just testing that piece of crap software, turned out it's a piece of crap. Uninstall lucid logix.

Edit:
I'm actually mining away with two 5850's now, on litecoin. Prior was one 5850 and mining bitcoin, I believe.

Bought the last two cards, Awaiting arrival.

Everything fab as usual, Thank you for another flawless trade.