Good Dual Graphics cards or gaming

Hey lately ive been trying to help my brother build his rig and im stuck at the graphics card he wants somthing for some moderate gaming not for high demanding games like crysis 3 on max settings but more like med-high settings. Ive been thinking of going the radeon way but i still think geforcecould be better. For the Geforce way im thinking maybe 2 650s Geforce is limited with the middle end cards so not much choice and with Radeon im thinking maybe the HIS HD 7770 with the icooler or the or the xfx 7750 depending on the color scheme of the computer but for sure want to run 2 graphics cards together, dont really know how the crossfire thing works is it like SLI where you need the bridge?

This may not be pertinent but I would think that there are a few important things you left out...

1.- Budget you have to purchase the two cards

2.- System specs of the Rigs you have now or will built for your brother

3.- Is he playing Online or more like Solo Campaigns... what Genre does he plays the most?

Does he (or you) want two cards because you think or heard its better or because you know for a fact that it would be better for gaming? just asking. Personally, I have gone the SLI way and I found ZERO progress with them. People tell me that it was because I did it when Games did not worked well with SLI and today they do.

Then I ask myself... I only play Shooters and most of them are Unoptimized/Bad coded Console ports so do I really want to believe they are programmed to take advantage of SLI/Xfire? if my system specs are on the low side, would I do better with 1 card than perhaps bottlenecking the system with two? See... more questions than answers at the moment

He says mainly Crossfire, StarWars The Old Republic, League Of Legends, COD, and lots of photo editing. I dont think these games are very demanding. Looking for a sort of low budget i think 300$ is the max for graphics, most games are online. Yea ive heard and seen the benchmarks for sli and crossfire most seem higher i believe if its dual cards its less stress then if it was a single card. System specs havent been fully decieded yet as he wants to build a new system but this is what we got so far.

-i5-4670K @ 3.40
-Gigabyte GA-Z87X-D3H
-ThermalTake Armor Revo Case Black
-3TB Barracuda @ 7200 RPM
-Viper Black Mamba 16GB PC3-15000
-PSU not known yet

I've got an AMD Radeon 7870 that I bought for around $200+. I'm running it on an i-920 no overclocked using 2 ASUS 25" monitors. I also have the HDMI going to my 50" LED HDTV. Everything is fine. The card is quiet and I'm running Crysis 3, which came with the card. Aside from the fact that I'm super lousy in games...I die frequently, the Crysis looks fantastic. I'm using all the defaults except I've cranked up the brightness pretty high so I can see better "in the dark."

I will admit that if I did it all over I might stick to nVidia and get one of the 650 series cards as they cost about the same. The AMD software is not well documented so if you want to do more then just run the card you'll have to do a lot of trial and error.

I use the presets in Catalyst to change from dual screen 1920x1200 to single screen 1920x1080 to output to the HDTV. I finally found a way to set a preset to do this. At any rate, you can get a butt kickin' card for around $200 that will be more then enough.

If you want to go with a multi gpu option, both (sli & xfire) are going to require a bridge. To address your current options. I see your considering a 7750, 650, and the 7770. If you are dead set on choosing between one of these. I would recommend the 7770. It will give you more performance than the other two cards specifically for Call of Duty

As mentioned above, in some games an Xfire or SLI config may give you or your brother some trouble. Depending on how much googleing and tinkering you or he likes to do I would also recommend a single gpu option. At the budget you have set of $300 you can get a GTX 760 with some money to spare. The 760 is on par with last generation's 670 which is an excellent card, and CUDA will give you an edge if you use CS5.

What photo editing software does he use?

linnemeyerhere that sure is one godly graphics card! Well i guess we will go with the single GPU probably that 760. I dont even thing my local reseller sells that windforce card o.O the best we can get is the Evga one not that im complaining. I love Evga always will. Will the 760 bottlenecked by the cpu? its only 3.40 and will have to go with a 700+ watt PSU just in case