The Nvidia GTX 970 is a game changer in terms of performance per watt and value for money. The GTX 970 is based on Nvidia's ground-breaking Maxwell architecture which delivers considerable clock for clock performance gains over Kepler, its predecessor. Comparing the GTX 970 and 780 Ti shows that the two cards offer comparable performance yet the new GTX 970 costs nearly half as much! Unsurprisingly Nvidia are discontinuing the 780 Ti as it's now largely redundant. These price to performance gains typically occur once or twice a decade and although the new Maxwell architecture will improve down the line with the release of the Ti/Titan versions, at the moment the 970 offers the best value for money on the market by miles. Since this summary was originally written AMD have slashed prices and older Nvidia models (780/780 Ti/770) have also been hugely discounted. See the latest value for money rankings here. [Jul '15 GPUPro]

The GTX 1070 is Nvidia’s second graphics card (after the 1080) to feature the new 16 nm Pascal architecture. As a result of the die shrink from 28 to 16 nm, Pascal based cards are more energy efficient than their predecessors. The GTX 1070 is rated at just 150 Watts. In terms of performance the gap between the flagship 1080 and 1070 averages 25%. Both GPUs have 8GB of DDR5 and although they share the same processing core (GP104), the 1070 has 25% of its resources disabled. Comparing performance between the 1070 and legendary GTX 970 shows that the newer 1070 wins by a whopping 50%. The GTX 1070 has only just hit the market so, at least for the time being, prices are significantly over the Founders Edition MSRP of $450 but Nvidia have stated that they expect third party cards to sell from $379 at which time the 1070 will likely dominate as the value for money leader. [Jun '16 GPUPro]