Bottlenecking.

[PigonGamer]

  I've had this computer for a while, but it's always been slow, and I don't know what to upgrade. My current CPU is a Core i7 930 @2.8GHz. I have 12 GB of DDR2 memory, a 802.11ac Wireless LAN Card, and an NVIDIA GeForce GTX 660. I primarily use this PC for gaming.

If any more information needs to be provided I will describe what I need to, and, if someone could help me out and explain what needs to change I would really appreciate it.

[Frankenburger]

All in all, you're probably going to want a whole new system. But if you can only afford to piece upgrade, I'd say GPU first. That way, you can run games at higher graphical settings, even if your FPS is being capped by a CPU bottleneck.

[Light-Yagami]

A fighter, but ancient at this point. You need a new system from ground up.

[Fasauceome]

Didn't know there were motherboards for the 930 that supported DDR2. Still, you could do with a better graphics card. Try a GTX 1050 off eBay, it's rather low power but much better than your current one.

[PigonGamer]

Thanks for the solutions, you guys. I'll check out GTX 1050's and save up for that first. Then, I'll go for the CPU and the rest.