In some cases, a 1st gen i7 can bottleneck a GTX 980 or faster if not overclocked. A 4690k will not bottleneck any single GPU. If you need more efficiency, the new Broadwell i5-5675c will run much lighter in wattage.
http://ark.intel.com/products/88095/Intel-Core-i5-5675C-Processor-4M-Cache-up-to-3_60-GHz