If you're into gaming hardware, you would most likely have your own take on what SLI(and ATIs crossfire) is and if it's worth the trouble
Im not going to go into what SLI is... there are zillion places you can learn about nvidias Scalable Link Interface technology - including the official site
Great tech discussion article about SLi at Hexus.net
Nvidia's official spiele her at SLI zone
If you want something a bit more general, the SLI Wiki
isn't too bad.
Having beta tested vista drivers(pre release) for SLI, having used a SLI based PC in xp gaming with the 7950GX2 - Ive had a bit of experience with it.
I will give a summary of pros and cons from what I experienced - it will be interesting to hear others take on it:
*Optimised for high resolution gaming - with high end games. As someone with a 1600p monitor, the idea of running a game super smooth at 2560 x 1600 with all effects maxed it quite appealing.
This is where SLI has been *proved* to shine.
Over @ AHTO, NegSun and I were discussing the 7950GT -which is still a decent DX9 card.
There is a super article here - showing what SLI can do with the the 7900GTX
To give a sample of what you will see - have a look at these numbers for FEAR. Can you really argue that SLI is pointless in an ultra hi-def context ? I think it is quite difficult to !!
*More games recently with SLI optimisations... most 'next gen' high end PC games will include them as standard
*If you have a compliant mainbaord - 2 older cards will get you more longevity. Look at the numbers for the 7900GTX in SLI !!
*power - 2 cards suck more juice than one
*heat - due to the above
Although most people that build SLI rigs have thought about thermals well in advance, so work to minimise this with extra fans, watercooling etc
*Cost. Especially if you want the *new* stuff. eg. an 8800GTX Ultra SLI setup will cost you the price of a small (used) car
*Games - there hasnt been a huge amount of games that have SLI enhancements. I mainly remember enabling it in COD2.
*DX10 shift and Drivers - SLI was only recently enabled in a WHQL driver release for the 8 series GPUs. With devs and the manufacturers playing catch-up with Vista, tech wise - we are currently in a DX9-10 limbo - which is quite unusual
What I find annoying is that the manufacturers keep thundering on releasing new tech where the full potential of existing tech hasnt been properly flashed out. eg. The nvidia 9 series GPUs are due late this year, early next year.... They are nowhere near maximising the potential of the 8 series - they should slow down a bit and concentrate on making great drivers for what is already around... IMO anyway
x64 operating systems have also not been exploited to their full potential.... it is comical to think that 64 bit CPUs are standard now...but they are almost always sold in an x86 platform. Whilst I am pleased Vista x64 is quite stable, it is merely because MS has done a great job developing x86 emulation in Vista 64....
The ideal pc standard for high end gaming:
*Quad Core CPU
*SLI/X-fire capability or high end single GPU
*Bluray or HD-DVD drive
currently, we only get close on one of those...the gfx card. I think there are a good few years before there is an x64 shift in the gaming world... it definitely is for the better...because the high end hardware that is coming will need to be backed up by the ability to play with over 3GB of RAM...
time will tell, and our wallets will suffer