1) GTX970:
- excellent value, however suffers from the "slow 512 memory" issue which appears to cause STUTTER in many games that use more than 3.5GB. It's difficult to find reliable info on that in part because few games use that much memory currently.
I kept hoping NVidia would produce some simple option to LOCK to 3.5GB for games that showed stutter but for now there's no obvious fix for these scenarios.
For MOST games currently it's an awesome card just keep this in mind.
Recommended GTX970:
http://pcpartpicker.com/part/evga-video-card-04gp42974kr
2) GTX980:
- does NOT have the "slow memory issue"
- roughly 15% faster on average than comparable GTX970 (slightly LOWER for CPU-dependent titles when using the 2600K since tests are done on newer CPU)
- less of a value
**Please note that the PRICE CORRECTION due to the GTX980Ti probably hasn't happened yet. Supposedly the cards will drop about $50 since the GTX980Ti reference is a much better card at $650USD.
Recommend GTX980:
http://pcpartpicker.com/part/asus-video-card-strixgtx980dc2oc4gd5
There's a couple models I like. I do recommend one that can disable the fans (zero noise) if that's desirable to you. I'm not sure if Gigabyte offers this. EVGA, MSI and Asus do.
3) AMD??
Pros and Cons but I mostly can't recommend.
- many models have quality issues
- produce more HEAT dumped into room
- much NOISIER than 970/980
- lacking several features that the 900 series has (H.265, MFAA... and more)
I have recommended the R9-280X for the cheaper price segment though.
*Look at the GPU comparison link below and note that the GTX970 beats the R9-290X on AVERAGE (about 20 games) and that doesn't even count titles that support MFAA (AA method which can boost frame rate higher). When I checked pricing there wasn't too much difference between cards I considered comparable quality.
Summary:
GTX970 recommended if the slow memory issue doesn't concern you too much, otherwise I recommend the GTX980 after the price correction which I assume is coming.
Otherwise you can WAIT for newer AMD but not sure when that's coming and most are rebadged GPU's. So far I'm only aware of the R9-390X which I assume is competing with the GTX980Ti? So not quite sure of that situation.
Pricing for NVidia right now is a bit weird. The GTX970 is awesome but has the slow memory issue. The GTX980 doesn't but is a poor value currently compared to the 970 but also compared to the 980Ti.
At $650USD the 980Ti is a really awesome card but then it's about 2X the price of a GTX970 which can max or near max-out many games anyway.
Here's some more info:
http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_980_Ti/31.html
**DX12**
When DX12 games come out they should use your CPU a lot more efficiently. There's a pretty good chance you'll little or no CPU bottleneck at all unlike some current games. Hard to say how long DX12 will take to become standard but it's worth considering when thinking about upgrading. You may find your system can last you a bit longer.
W10 is required but it is a free upgrade. I'd recommend waiting until closer to Christmas for a few more things to be sorted out. I'd also do a clean install so plan accordingly. Or you can do a bit of research to see how successful the upgrades are but in my experience usually something goes wrong or isn't quite optimized.