Hi, i'm quite new to this. I've heard that running on SLI and Crossfire increases the graphics performance by 60% but also the disadvantage is that it slows down your Hard Disk Performance. To solve this problem you can just buy an SSD but in order to fit the "Budget" would it be worth to install 2 example GTX 460 or one GTX 580?
HDD performance has nothing to do with it, you will higher average fps and usually a bit lower, current generation of amd and nv dual gpu setups tend to scale up to around 160% so don't excpect double the performance, in my personal opinion I prefer a single powerful card and then down the road sli or crossfire it if it makes sense. Another thing you need to consider when crossfiring high end cards is that you need a good cpu with ample overhead to maintain and control 2 cards, in my personal expirience with crossfiring 6870s, they worked like crap, the minimum fps suffered and the overall expirirence had all this sporadic stuttering it was annoying, my avg frames were high but my cpu and poor crossfire drivers held me back, since then I abondoned the 6870s and am currently selling them on ebay and I picked up a single gtx 570 and oc'ed it now it gets identical numbers to a 580 practically... my 2 cents
sli generally offers better minimum frames (on the high end) when going from one card to 2 there is very little loss in minimum fps which truth be told is a very important spec that many gpu reviewers gloss over imo,
you do not need an ssd to do crossfire the hierarchy of things you need are as follows.
1. Ample CPU
2. Ample PSU
3. Capable motherboard preferably dual 16x slots for when aa and af are really juiced, although 8x8 will suffice, if you were going for a high end crossfire setup I would pay the extra few bucks for a 890FX board..
4. 7200 RPM HDD