nah it was worth it since 4960X doesn't support DDR4
DDR3 hardware prices will dramatically drop soon, so its the best time to upgrade now
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i don't think so since those blacks were mainly designed for lower resolutions than 4K, talking about bandwith speed and vram size...
besides that the titan x supports dx 12 and has a way better efficiency and they should perfom about the same if not better as 4x titan blacks in 4K