Help with a semi stock build

[Faisal najjar]

I will give you everything i know then continue to ask about my problem.
I had a hp h8-1414:
http://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c03517389

Then i decided to upgrade psu case and graphics card, simple so far.
I got a gtx 750 sc:
http://www.amazon.com/EVGA-Superclocked-Dual-Link-Graphics-01G-P4-2753-KR/dp/B00IDG3LUO

And a case w/ psu ( i just now looked it up and know the psu is garbage):
http://www.amazon.com/gp/aw/d/B00FSVL1CM

1. But here is what happend, i plugged the new graphics card and all the stock components into the 500w psu and it failed to turn on anything... But the 300w oem power supply that came with the computer from the begining powered everthing and the new graphics card.

2. My computers UEFI interferes with the new graphics card so i looked at how to fix it and so i learned that i need to turn sercure boot off and legacy boot on. It worked but the problem was not that it was that it took ages to turn on and then after that it took ages to log into my user but after that it was really good ( as in open programs fast and ran games well).
Also whenever i would open borderlands 2 it would work until i would go to continue game then it would load my character holding the gun then instantly stop responding. But i played league of legends and it was perfectly smooth, same with minecraft with shaders. I also tried turning the borderlands setting to low and the problem still persisted.

I went on the nvidia website and got the driver for my gtx 750 but thats the only driver.

 

[AdviserKulikov]

PSU might have been dead on arrival, it happens. Speak with their tech support about possible solutions/return.

Check for updates to your uefi. They may offer a new revision that supports the GPU.

 

[Faisal najjar]

PSU might have been dead on arrival, it happens. Speak with their tech support about possible solutions/return.

Check for updates to your uefi. They may offer a new revision that supports the GPU.

what about borderlands 2, any idea? Should i try redownloading?

 

[AdviserKulikov]

PSU might have been dead on arrival, it happens. Speak with their tech support about possible solutions/return.

Check for updates to your uefi. They may offer a new revision that supports the GPU.

what about borderlands 2, any idea? Should i try redownloading?

If it's steam, check the game cache integrity (this is a much better method as it avoids possible write/transmit errors involved in a full size download). Otherwise you may consider a normal redownload.