Here is a photo of my 5750 in its current state. I intend to do some pretty heavy modifications on it over the next couple of days, so I will be sure to post progress photos here.
Hard vcore mod is a go. I also have added a molex connector for easy reading of vcore, and the fan is now soldered onto the board's voltage input, so it will no be limited by what the built-in controller can supply.
Here are pictures.
I just need to work on something for vmem and possibly a better cooler mod and this thing will be epic.
^^^ I prefer to have one powerful card as opposed to crossfired ones unless you already have 2 and are looking to add a third. You would also have to make sure you PSU can handle it as well. But the thing is it is not like just adding 1 more card and using crossfire with 2. You are going to be gaining some but not as much as you would really think. AFAIK once you start putting multiple cards you lose some of the gains you would get with each one. For example if you have 1 and add another its not going to double your power now because you lose some of its full potential. You are still getting an increase but its not double. Then when you add a third you will still lose some of its potential meaning you wont get 3 times the power but maybe only like 2.4 or so. These are not exact examples and I am not saying you will definitely get an increase of this amount but you will not get the full power of all 3 cards because you lose some of their potential.