d359233drdrbcom :
I have two more questions:
can anything except temperature and voltage degrade gpu?
(I have 377 usd to spend on radeon for gpu mining and a psu.I will probably buy psu from europe and gpu from USA)
Most cheap psu brands are less known
is there any way to determine psu quality if no one has ever bought it?
If a PSU puts out high levels of ripple on its outputs it will eventually destroy the electrolytic capacitors on the graphics card, motherboard, hard disk controller circuit board, etc. That's why power quality is extremely important.
Knowing the OEM and its OEM platform of the PSU is a way to determine its quality. Seasonic is considered to be one of the best. Seasonic has its own retail models under the Seasonic name. All of XFX's PSU models are made by Seasonic. Most of Antec's High Current Gamer models, all of the True Power Classic and True Power New models, some of the Neo Eco models are made by Seasonic. All of the currently available (i.e. not discontinued) Corsair AX models are made by Seasonic. The Cooler Master V Series are made by Seasonic.