hummm... what to do... swap in a r380 or buy another r 280

Lets see here with the prices of a 280 and 390 being so close to each other $260 vs $325 should I just add a card or just replace it outright with the more powerful single GPU card?

I do have a 750W PSU that is not being used

xfire? i am having that same problem but its between a 290 and a 390 lol

Sell your 280 and just get a 390. That is not a typo correct? an actual 280. Considering the 280X crossfire is only about 10% faster than a single 290X, Crysis 3 comparison of 280X SLI and single 290X , dual 280's are going to be slower than the 290X then. From what I can tell the 290X and 390 are pretty close, with the former being slightly stronger. It would seem silly to spend another $260 to not be guaranteed higher performance across the board. Getting a 390/290X should be all around way better because of no worrying about crossfire working while being on par or better while costing you less.

Edit: I'm slightly confused, your title says to replace with a 380, but you talk about replacing with a 390. If you are considering a 390, you can get 290X yet at 290$ after rebate.

just buy the 390 or what ever then sell your other card....one card is better than 2

should be 390