Is it enough ? Depends on your goals. You did say that you were planning on spending $8k so I expected those goals to be somewhat lofty
.
The most common request I get is "I want 60 fps in **all** games at 144 Hz for at least 18 months.
No single GPU can do that today other than the Titan X
Is it overkill ? If your goals aren't very high, certainly. If you are willing to make compromises and turn down settings ..... and aren't using 144 Hz / or G-Sync, I wouldn't bother. But I really can't see buying a 60 Hz monitor these days
Look at it this way....
A 980 costs ya $550 and ya get $60 coupon for Witcher 3
Two 970s cost ya $646 and ya get two $60 coupons for Witcher 3
So if ya sell one coupon to ya best bud at a $10 discount...then it's $596 for the two 970s which gives ya 50% more fps than the on 980.
The one 970 gives ya
42 fps in Crysis 3 and just under 60 in Tomb Raider at 1080p.... but with an anticipated system life of 3 years that list will grow quickly .... I expect Witcher 3 will start the flow of games that start to overcome the 970 and XMas 2015 will no doubt add more.
And the coupon thing expiring in the not too distant future, I'd do it now. One 970 is certainly not going to deliver 60 fps for an expected 3 year system life.
Also helps to make sure ya get the same cards .... on a recent builds we've done w/ same model cards, one had Samsung memory, one had Hynix.
We have had requests for more 970 SLI builds than 970 builds by about 3 to 1 .... and the ones that went single did so for budget reasons but did include an SLI capable PSU.