GPU Time Lengths
Your question doesn't make that much sense though. Of course two 980 Ti will last you 3-4 years. Even an RX 480 will last you 3-4 years. Hell, integrated graphics will last you 4 years. If you expect to play games at max settings and >60 FPS then probably not. Dual 980 Ti will have a hard time doing that today even.
Your question is also impossible to answer because we have no idea what games will be like 4 years from now.
1300 dollars for two 980 Ti seems really expensive by the way. You could get two GTX 1070 for like 850 dollars and they will perform way better.
Historically, it has been much better to buy what you need, when you need it. Price to performance has just been going up so quickly that it didn't make sense to spend 50% more money on something because that 50% only made your computer "last" 5% longer, if you get what I mean.
We are not too far away from two new generations of GPUs. We got AMD preparing Vega for a release later this year, and Nvidia might releases Volta as early as next year. With that we might get awesome stuff like 3D memory.
AMD might also release Zen within the next few month, and we have no idea how good/bad that will be.
My point is, it's impossible to tell you how good a computer you plan to buy several months from now will be several years from now. Anyone claiming to know that is naive or lying.
What you should do
1) Wait until it's about 1 week left until you order your computer.
2) Make a list on PCPartPicker so that it is easy to see which parts you plan to buy.
3) Tell everyone which country you live in so that you don't get a bunch of people recommending stores in the US if you are in Canada or whatever.
4) Tell everyone which programs you use today, and plan to use in the future. Don't say "I want to use the latest programs". Be as detailed as possible, such as "I plan to live stream using OBS" or "I plan to edit photos with a program such as Photoshop".
5) Don't expect a 20% increase in price today to make your computer last 20% longer. It's usually a lot better to buy parts with good price:performance ratio and save any money you might have left for future upgrades. Just look at SSDs. Four years ago you had to pay about 200 dollars for a half-decent 250GB SSD. Nowadays you can get a fast 500GB SSD for 160 dollars.
It is a good idea to not cheap out on things that do last a long time though. Things like cases and power supplies don't get outdated the same way a CPU or GPU does.

Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now