No offense to renz, but I have had about 12 different GPU combinations, some with one powerful GPU (1X GTX 480, 1X 8800GTX), setups with ONE card with TWO GPU's ( 9800GX2, 4870X2) other setups with 2X medium range GPUS (like 460 in SLI) and also very powerful cards together ( 5870 crossfire, GTX 570 SLI, even Tri-fire 48701GB).
The point I want to make is that I know what I am talking about when it comes to single, double, and even multi-gpu setups.
While it is true that microstutter was an issue with crossfire/SLI ( I noticed this on my 9800GX2, and a little bit on my 4870X2) The problem is just about dissolved these days. Anyone who is still claiming microstutter either does not own a current gen SLI/CF configuration, or has not experienced the phenomenon themselves.
When it comes to driver support, anyone will tell you that these days, driver support for multi-gpu support is just as good as single card setups. Now the drivers themselves may be poor (Every now and then Nvidia and ATI just let out a dud driver) But poor driver release will affect everyone, and not usually specifically those with multiple cards.
While I will not contest the point that 'some games do not like multi-gpu stuff at all' there are few games these days that fit into that category. Most games these days that have issues or will not work with mult-gpu setups, are games that are easily run on a single gpu anyways. Games like Killing Floor, and Sins of a Solar Empire would fall into these categories, also indie titles like Penumbra, or VERY poorly ported games like Mercenaries 2. The point is, any game worth playing these days either has support for multi-gpu setups, or can be run easily with one GPU. And turning off SLI or Crossfire takes a few seconds if you should need to do that.
The last point I would like to expand on from renz's post, is the topic of scaling. These days scaling is almost always at 80% or higher, long gone are the days of 50% scaling and lower. In fact, in many games scaling is around 95-100%, sometimes even going past 100% scaling (although extrememly rare).
Obviously I am a big supporter of mult-gpu setups, there is almost no reason not to, unless there is a power supply or budget restraint.
To answer your direct question ( I did not mean to ramble, but I don't want you to be misled) You would be much better off selling your GTX 285 and purchasing two GTX 460 1GB for SLI. You simply cannot get better performance for your money. Not to mention DX11, which often times will INCREASE fps just by using that API.
Go for it, good luck.
Facebook
Twitter
Instagram