Why do graphic cards need a power supply?
Ok, I know this kinda starts off like a dumb question, but my inquiry is, after spending months trying to find the right combination for PSU and card, I started thinking, why can't like graphic cards come with something like a transformer you can plug in directly into the wall outlet, like it's own private little supply unit. It would help a lot when wanting to buy a graphic's card without having to change your whole PSU
Well usually when you buy a good enough PSU it will last you for a VERY long time, once you upgrade if you do it smart you are "set", E.G. my 750TX should last me a while.
The solution you call for is impracticle and I don't even see how it could work correctly.
Finding a good PSU and GPU combination shouldn't be hard at all, if you like we can help.
Because you need to convert Alternating Current to Direct Current for the video card to use. Sure you can build a video card with it's own converter, but it will add more cost, umm... probably $40 - $80 to the cost of the card for the additional components, it will be somewhat large taking up 3 slots, and may inhibit airflow.
They do have dedicated power supplies that fit into 5.25" drive bays for GPUs but they are usually quite expensive.
Much of the systems in a PSU are the same size whether its a 300W unit or a 1kW unit so you wont end up saving much space by making a separate dedicated unit, however, you do end up with yet another wire running to the computer, and yet another power cord. If you made it like a power brick it would get super hot when it was running at full load, the biggest laptop power supply i have seen is like 150W, some GPUs would need up to 300W power supplies which would generate quite a bit of heat and you run the risk of it heating up and starting fires. The SMPS design used for modern power supplies is fairly efficient, reliable, and cheaper. I bet you would find that a 300W power brick would cost more than a 750W power supply so it wouldnt be worth it for anyone involved.
Where did you find it for $20? I found it on amazon for 85 and that was one of those dedicated graphics power supplies i had mentioned.