What kind of rating on the 12v rail would i need for twin gpx cards?

It's not actually for running in SLi but for a triple monitor setup. So one card does all the work & the other acts as output device.

I currently have 22A on my 12v rail would this be enough to run two seven series cards?

Should be enough if the second card is only a small one.

what power psu do you have and what 7 series cards?

Normally the PSU's that are compatible with SLi are marked "SLi Compatible".

Normally they're at least 650w and have the required amount of 6pin PCI adaptors. (Bear in mind most cards nowadays require 2 to work, so including the Molex>6pin adaptors, you need a total of 4 6 pin power connectors to get 2 top end cards in SLi)

For a buget, I suggest the OCZ StealthXStream series. For proper performance though, Corsair are pretty good.

if one doesn't have to do 3D, there is no reason you can't get a simple card. Saves money and won't matter in performance, plus the extra wattage will be low and you wouldn't need a new psu at all. 22A = 264Watts, vs some 80 W for a 7900GTX ( http://www.xbitlabs.com/images ... /geforce7900gtx/power.gif ) Unless you have a silly quad core monster with lots of harddisks you should probably be fine.. plus there is unlikely to be a need for two GTX cards when one just does 2D.

One does want to use it for playing LFS so I will have to use a card capable of doing that. I do not have a monster system so not much drain on the PSU from other sources.

I think I will just try it out & see what happens. Worst case scenario is my PC just crashes or shuts down.

Quote from anttt69 :

One does want to use it for playing LFS so I will have to use a card capable of doing that. I do not have a monster system so not much drain on the PSU from other sources.

I think I will just try it out & see what happens. Worst case scenario is my PC just crashes or shuts down.

Exactly. See what happens with what you have and move forward with a nicer PSU if needed.

Try out this calculator to measure your power requirments:

http://extreme.outervision.com/psucalculatorlite.jsp

Good Luck

jay