I purchased a diamond Radeon HD 7750 to upgrade a prebuilt I bought yesterday. I sat there for literally 3 hours trying to figure out how to plug the damned thing in to the PSU, until I finally realized it doesn't even have a socket for a PSU lol. So my question is - If the requirement for the GPU is 400W, but it doesn't need a PSU plugged in to it, how is it going to get that power?
With its pared-down, lower clocked, GPU, the Radeon HD 7750 requires less power than the Radeon HD 7770—55w vs. 80w. As such, the Radeon HD 7750 does not require and additional power feeds. The standard 75 Watt power budget provided by a PEG slot is more than enough. The Radeon HD 7750 also has a much shorter 7” PCB and a single-slot cooler design.
The pci express slot on it's own provides enough power for the 7750. The 400w requirement is overall power consumption for the whole computer with this card.