My friend has just got an XFX nForce 780i mobo and he has two Gigabyte 8800 GTS 512mb graphics cards.  So we were thinking he'd have a pretty awesome rig once its all together and running.  But SLi just isnt deliver the performance it should... infact it makes games run worse.

We've tried everything to get SLi working properly and had no luck.  We've tried both xp and vista (both 32 and 64 bit versions), we've tried updating every driver we can think of, we've tried SLi bridge round one way and around the other way, we've tried everything in the nVidia control panel, we've tried yelling at it, we're tried the cards in the opposite order, we've even tried readig the manual!!!!!

When we first booted the machine up after putting in the 2 graphics card with the sli bridge on, we got the usual message saying this is an sli compatible yadda yadda yadda so naturally we said yes to all that, but still got poor results, tried changing every setting in the nvidia control panel (took forever) but still cant get any decent performance out of it.

Hes got an 800w power supply and a core 2 quad 6600 chip.  4gb (2X2gb) ddr2 ram running at 800mhz.

He gets a better 3dMark 2006 score using one card than he does with two!  We are getting power straight from the powersupply to the cards instead of going through the 12v hard disk connectors with the Y shaped adapted on them.

If anyone could shed some light on this for us we'd be most grateful.

Sorry if I posted this in the wrong place, no doubt it will get moved if I got it wrong.