PSU + Mobo + GPU = Compatible?
Hi - Yes, compatible, and enough to power a system with 2 - 290x's. Also, a z87 mobo does have the approp socket
for an i7 4770k, and the TX850 V2 has the 4 - 6+2 pcie connectors required.
The PSU should be fine, R9-290X power consumption http://www.guru3d.com/articles_pages/radeon_r9_290x_review_benchmarks,10.html
When you CF 290X, you need 2X6pin and 2X8pin, and the PSU has all those pcie power connectors.