AtenRa
Lifer
- Feb 2, 2009
- 14,003
- 3,361
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This is an illogical way to measure a card's improvement in perf/w in so many ways.
1. New halo cards from Nvidia have no equal in performance, and therefore based on your logical have an infinite improvement in performance per watt.
2. The GTX 750 TI matched the GTX 480 in performance, but in no way was replacement to that card to anyone with a half brain.
Similar die sizes or same family hierarchy is the most logical way to measure perf/w improvements. The RX480 slotted the exact same way the 270x was with relation to price, die size, and performance amongst the rest of it's stack so therefore that is the most natural and logical comparison.
Technically we are always using perf/watt with iso perf OR iso power for consistency.
You can see this in every Lithographic process , they always compare at iso perf and iso power vs the previous process.
Now, if you want to use perf/watt for PR etc, you can use what ever context suit you best, like same die size, same prices etc. or when AMD used TDP to come to the 2.8x "perf/watt" of RX480. That was pure PR and nothing else, but actually RX 470 had at the time of release almost double the perf/watt (power ~120W for both) against R7 270X at 1080p gaming.