The R9 290X draws 250 watts and the R7 240 draws 50 watts. Both cards are spec'd for PCI-e 3.0. This tells me that ALL of the bells and whistles of the R7 240 at just a 50 watt draw will appear on screen in all of its glory, although at a lower (1280X720 perhaps?) resolution. Meanwhile, the add on 6 pin and sometimes 8 pin power cords draw off the main power rail from the power supply for video cards that draw lots of power and they too should produce ALL of their bells and whistles as long as the plugs and power supply provide sufficient watts. PCI-e x 16, PCI-e X 16 2.0, PCI-e X 16 2.1 and PCI-e X 16 3.0 only provide power. If sufficient power is available, the card will do its job. For the majority of games, the cards are fine even with marginal power and only a select few games give problems to even the biggest, baddest cards out there. (Its the software, not the data) If you have a weak power supply, I'd advise cards without a six plug supply cord up to cards that just barely need a six plug supply cord. You have to obtain the power draw stats and ignore any video cards that draw more than 75-80 watts. Even then, you can get away with lower resolution to save power. You will still have all the detail however. And if your LCD/LED monitor has a native resolution of 1920X108, it will upscale the image and fill every pixel.