Is it worth spending the extra money on SLI technology?
Well... with no information at all I have to ask
1. What Card do you have
2. What are you using it for, Be specific like if its gaming... at what Res and what kind of games
3.Are there better alternatives like more powerfull cards instead of more cards
Im going to build a PC for gaming, 1080p and my other option is the exact same card but without SLI for about £50 cheaper.
SLI is the running of two cards togethe, in parallel, for combined computational and graphical performance for gaming, mostly (many editing apps do not support SLI or CF). What card are you looking at? If it doesn't support SLI, then it is a really, really old Nvidia graphics card, or a professional series card (probably out of your budget.)
The card is the GeForce GTX 650 Ti SC
For the money of a 650 ti Boost, get a 7850. More powerful.
Is it?
Nvidia:
Core clock= 1072 MHz
Memory clock= 6008 MHz
Radeon:
Core clock= 860 MHz
Memory Clock= 1200 MHz
You can't compare them like that.
You have to look at benchmarks.
You can't just compare clock speeds like that across manufacturors. The GPU cores are so different that it doesn't make much sense. For example, a stock 7970 has a core clock speed of 925mhz and it would whip the holy hell out of that 650 ti at literally any game or benchmark.
All you can reliably look at to gauge performance is benchmarks. Recent benchmarks at that, because drivers get better over time. And even then, some of that performance is tied to your CPU.
So really, go find benchmarks for the games you want to play, from a variety of different sites. If you can find a 7850 for the same price as the 650 you're looking at, I'd say that's a great deal.