Hi guys, I am sorry for the delay of my answer but as I am teacher my days are totally crazy going everyday to different places.
Anyway, I appreciate your help but the problem are prices here, those psu you recommended are between 50% and 100% more expensive than the one from Gigabyte.
Also I have some cases in mind that I guess all of them are cheap and they have good airflow (but they arent so nice to see) and maybe you know if some of them isnt good enough.
Genesis Titan 660 Plus
GAMDIAS Argus E1
SilentiumPC Regnum RG4TF
Aerocool Bolt - black window
In the other way, I was thinking how bad could be buy a used psu and if it is totally not recommended.
I saw COOLERMASTER V850 Vanguard GOLD 12V-70A 850W and also Cooler Master M2 Silent Pro 1000W 80+ Silver for the same price than the Gigabyte.
I don't know how bad could be to buy an used psu and how could I test it before conect to the rest of components.
In theory, the companies that are selling those used psu guarantee that everything works correctly and you can allways give it back for free and then they returned the money, but as I told you, it's gonna be my first pc, I have not to much money and I will try to do something that I don't need to upgrade in the short term.
I know it's a lot of things that I am asking for, but any answer you can give me, it will be valuable information for me.
Regards!