I'm building my second PC and just checking it'll all work as it should :)
CPU: Intel Core i5-4670K
GPU: 2X MSI Radeon HD 7970 Twin Frozr III/OC Boost Edition
Motherboard: MSI Z87-G45
PSU: Corsair 800W Gaming Series GS800
Case: Zalman Z12 STD ATX
Already got RAM and HDDs.
Opinions, and will it all work properly?
That will work fine, except maybe if you have multiple monitors crossfire has some issues with that, but you're pretty much good to go. Maybe swap out the 7970s for R9-280Xs because they're almost identical, with a few small exceptions, and cheaper in some cases.
It will work. what kind of monitor(s) do you have?
Edit: why not just wait a little bit and get a 780Ti or 290x?
I wanted too but I live in the UK and it'll be a while before the price comes down a bit, that and i hate waiting.
I'm only running one monitor with the exception of watching films on my TV.
Just the one and I'm mainly building a new one to make use of mantle because currently i have two 6870s and they're getting pretty old now so it's just going to be AMD for this build at least :)
I hate waiting for thing and see no reason to wait, the new AMDs in my price range it's pretty pointless waiting.
well based on what you said above you're pretty much set, everything will work and that will be a great system. Have fun building!
i would say go with the msi gaming edition boards they look nicer ☺ (personaly opinnion).