Yes, you missing something important.
You forgot that you need a quality case and quality PSU.
PSU - Much people don't want to spend money in a good PSU. Weird.. this is the hardware that will provide power to your system, and with a bad PSU it will eventually burn ALL your good components..
DO NOT BUY THIS PSU. IT WILL BURN/EXPLODE/HACK AND SLASH/DESTROY ALL YOUR COMPONENTS.
CASE - See if the case have a bottom placed PSU and a TOP opening for hot air. Side openings only usually don't have a very good flow rate.
EDIT: A good PSU for your computer should costs about 50 dollars. There's no magic. Good PSU, higher price.
And, btw, do no trust a lot when you see 750w wrote down. Sometimes this is a peak wattage, and not sustained wattage. Check if the PSU have a 80Plus certify. It helps a lot.
EDIT2: Just to make sure you won't burn your PC.
-> DO NOT BUY THIS PSU!!! <-
I am not familiar with Alpine PSUs. If it does not have full range active PFC (no little voltage switch, but operates on ~100V-240V) and some level of 80+ certification for efficiency, replace it with one that does.
The efficiency isn't the big deal here; the big deal is that even though they do it at an unrealistically cool temperature (23C), 80plus runs the PSU at its claimed labeled wattage for over half an hour. This would kill any of the cheap PSU-shaped objects out there, so it basically ensures that you're getting a reasonably accurately labeled product.
If you're not planning to add a second graphics card for Crossfire later, a good 500W PSU will be sufficient for your build. If you are, then 650W is enough. This may save some money, while still allowing you to choose a quality brand like Seasonic, Antec, or Corsair.
I've used an Alpine before in an old HTPC I had...it was quiet and I had no issues, but a HTPC is on light duties compared to a gaming rig. You definitely want a quality PSU otherwise you're asking for trouble.
A good case is reasonably important too where airflow is concerned. Heat is not a PC's friend, so you want to evacuate it as quickly as you can...I'd go with a case from a well-known manufacturer like Corsair over a no-name which may look OK but will probably perform poorly.