Upgrades?

So my PC right now feels to has finally started to slip up on performance. I don't play at 1080p my moniter is 1360x768 so I have gotten used to 60fps at max with my GTX 660 but it seems that is quickly come to an end and now I'm going to need to throw more money at that area of my PC. So here is what i have right now.

 

CPU - AMD 8320

GPU - EVGA GTX 660 SC

MOBO -  Asrock 970 Extreme3 R2.0

RAM - 8GB 1600mhz

PSU - BFG Tech GS Series 550w

So I have to upgrade my PSU either way and I'm getting a new MOBO for overclocking. If i wait on the MOBO i could get a 760 or I could go ahead with my plans and buy a second GPU. What should I do?

(added)

I do not want an AMD card at all. I'm sorry but I enjoy some of the things Nvidia has to offer.

http://pcpartpicker.com/user/deejeta/saved/3yR5 - way overkill on the psu so you can comfortably add in another 760 and oc the shit out of the 8320.

I'd probably save up for a better monitor before a new mobo though as that resolution is even bad on a laptop.

550W is plenty for most systems so you don't need to upgrade your PSU even if you got a better GPU and wanted to OC. You'll be fine there. 

If you want a decent motherboard the ASUS M5A99FX series are very good. Specifically the Pro and Evo are excellent and can OC very well. Not too expensive either. 

A 760 would give you a bump up in performance but the difference from the 660 won't be that extreme. I don't know specifics because I don't have much experience with those GPUs, but it should help you stay at 60FPS at your current resolution. At least for a while. May I ask as to why you don't want an AMD card?

I'd stay away from SLI if I were you. I have tried both SLI and Crossfire in the past and adding in a GPU is usually nothing more than extra headache. More noise, more heat and more power consumption for what, in most games, won't give you that much of a boost in performance. Very few games scale well to two GPUs. While some games you can get nearly double the FPS most of the time you'll see maybe a 30% increase. I don't really think it is worth it, especially when sometimes, in some games, SLI actually makes games run worse. 

I'd also look into a 1080p monitor. Hell even 1600X900 would be better than what you have. THat resolution is quite poor. 

Well I prefer Nvidia cards over AMD and i don't really care about 1080p all that much. From what I've seen in benchmarks out of all of the 600 series cards the GTX 660 tends to be the best scaler.

Ok I'm going to add that I'm in high school so i don't have a lot of money to work with. So if i go with the 760 i can't get the motherboard.

Why do you prefer it though? 

That could very well be true, but it is always better, usually, to go with a single GPU.