Tbh i have no idea as i dont have the gear to measure it on my test setup, i know the 750ti is TDP locked @ 38,5watts i have 2 of thees just for testing purpose. One of them is flashed to 65,5watts TDP while the other one is stock TDP. Crypto mining blog already did some testing on 750ti http://cryptomining-blog.com/tag/gtx-750-ti-power-consumption/ http://cryptomining-blog.com/3036-power-usage-of-geforce-gtx-750-ti-with-various-crypto-algorithms/
The r9 280x https://litecoin.info/Mining_hardware_comparison or simply google r9 280x dc2t 3gd5 mining power consumption there will be plenty of reading on people oc and undervolting thoes cards.
Hope that helped abit
The r9 280x https://litecoin.info/Mining_hardware_comparison or simply google r9 280x dc2t 3gd5 mining power consumption there will be plenty of reading on people oc and undervolting thoes cards.
Hope that helped abit
Unfortunately, unless they are specifically mining at NF=16, there's not really a great gauge. Because of the memory requirements of the coin, not all of the shaders can be utilized, so the card is running at a portion of it's full capabilities. The best way to tell is to plug your system into a kill-a-watt or similar device and take an idle reading of the watts, and then take a reading while running various mining configurations. You may find that a slightly lower hashrate (perhaps from a lower lookup-gap) yields a higher hash-per-watt, and that may be of interest to some people. I haven't taken wattage readings since NF=14, but I was measuring about 25W per R7 240 at that time, and ~32W per R7 250.
Not to mention the efficiency of the psu will also have a impact on the system as a whole. 25W from a R7 240 is nice, something tells me they will outshine the 750ti when NF gets even higher as you can get them in 4Gb versions compared to the 750ti with only 2Gb.