GPU Upgrade Time, but which one?

[Lewey52]

My rig is an Alienware Aurora R4 (yes I know, I bought instead of built. Mistake? Yes, but I was too lazy to build it this time around).

Currently it's running the following
- Dual NVIDIA GeForce GTX 660 with SLI (which I believe are PCIe 2.0)
- Intel(R) Core(TM) i7-3820 CPU @ 3.60GHz, 3601 Mhz, 4 Core(s), 8 Logical Processor(s)
- 32GB of Installed Memory
- 850 Watt Power Supply

The mobo I believe only supports PCIe 2.0, but isn't PCIe 3.0 backwards compatible with the 2.0 slots?

Anyway, if 3.0 is backwards compatible I was thinking of getting a single 980Ti and upgrade in the future to dual with SLI (may or may not need to upgrade the power supply)

Otherwise if it is not backwards compatible would it be worth getting 2x 780Ti?

Thanks!

 

[refillable]

Umm... With the 1080 coming out I don't see any reason to get the 980 Ti.

PCI-E slots are always backwards compatible. If you need it really badly, right now you can get the 980 Ti (the 780 Ti SLI seems like a bad option, it'll perform better but I'm not always a fan of multi GPU setups with the hassles). If you're playing on 4K, I can also recommend the Fury X for it's better DX12 support and performance.