How to find out the problem of the PSU or the video card or both?

Question

Iron

About two months ago, a friend decided to upgrade his PC so that he could play.

He had hardware 10 years ago BEFORE THE UPGRADE:
- mother Asus P7H55 chipset on socket 1156
- i3 530
- 2Gb ram ddr3 1333MHz
- Huntkey power supply unit at 550W
- no vidyuhi
- 500GB HDD

In general, he brought this miracle to me and says: help me improve, want to play. I named my budget and we collected it with the help of the local "Avito" THIS:
- they left the mother - they left the
PSU - they left
the railway, it was in normal condition
- 12Gb ram 1333Mhz 3x4Gb
- xeon x3470 (so as not to overclock, after all, the computer is not for itself)
- vidyuhu put RX 570 Gb Asus Strix Gaming
- the case is also old with the top location of the PSU
- and monitor 1920x1080

I checked after assembly, everything worked clearly, pubg, cs, dotA for which it was and assembled, they gave out quite stable and playable 80+ (pubg), 160+ (cs, dota) fps. These two months he has been playing well, today he came and says: seriously slow down the beginning in the games, look pzh. I open, really, hard friezes and in games there is a hard low FPS, in csgo at the minimum, a maximum of 60 fps. Reinstalled Windows, firewood, did not help. I opened the case, took off the vidyakha, I look at the gart on two contacts is small, but the line did not burn out completely. I looked at the pinout diagram for what the contacts on the video are responsible for, on which the specks of burning were formed: "+" and "-" power. I have never dealt with physical repair of a PC before, I plan to take it to the service. I am writing here to find out if this is some kind of bullshit that sometimes happens and you won’t have to go to any service. Overheating of the video card should not have happened, it stood at the furmark for 30 minutes, it showed a maximum of 83 °, the instructions and guarantee indicate that they are responsible for the performance of the video card only at a temperature of <90 °. The xeon does not have integrated graphics, but the computer works through the vidyuhi and shows everything fine. 1080p80 movies look fine, YouTube, video, photoshop, etc. they work ok, only in games the fps is hard low.

In general, my personal verdict:
Change the PSU and replace the connector on the video card, because most likely if there was a short circuit and the power supply went into the unit, then the connector should be coked. So that the situation does not repeat itself, the connector where the pins are connected should also be replaced. But I'm not entirely sure about replacing the pci-e connector on the board.

Answer 1

Probably, some of the power phases of the video card burned out, and it works at a small part of its power.
Checking is not so difficult, with a multimeter check the fuses on the 6-pin power line and the presence of a short circuit after them.
For more information about phase diagnostics, the repair process, and more on video cards, for example, here

Answer 2

The ideal would be an attempt to sell components and buy a used ryzen 3400+ kit