two times system run away

[johnyb98]

Good morning!
Please, I would like your help and advice on what would be the best solution in an office pc troubleshooting.

 

In the system of the office, it is a second time that a problem came out.
In the office there is no network. It is just a single workstation since 2013 of opening office-mini market.

First troubleshooting on January 2018 (no pc trouble since 2013 which is market opening)

 

The first trouble, on January 2018, was that, after workstation loaded Windows XP, and reached desktop, as you begin working, suddenly, screen got black. PC not turned off, just

screen got black.
I brought the pc in the lab, and opened the case. There was extremely plenty of dust in case. So much dust, that it was converted to fuzz. I took the very good blower that I have,

and remove all dust inside. After that, I connected pc to current, and started it up. First time seemed like it worked fine. The second time I started up (restart), the same thing

happened:lab screen got black. Because pc in the office-mini market all these years in not connected on a UPS, most possibilities is that no UPS, and, because all these years PSU

was working many hours every day, PSU would be right to be replaced. But, before buying a new PSU, in my lab I have an unused PSU and unused VGA for testing such cases. So,

I replaced PSU and installed PCI-x VGA and tested (the troubleshooting VGA is onboard). Everything worked fine after many PC's start up, and restarts. It seems that PSU is in bad

condition, and VGA is in a bad case, too. The much wondering is that, because VGA is an onboard VGA, trouble might be the motherboard. I risked it, and came in conclusion to

buy PSU and VGA. All these months it worked fine.

 

Second troubleshooting yesterday, Sun, 20 June
Since PSU replacement and a PCI-x VGA buy and install on January, no trouble came out until yesterday. Yesterday, opening market, my customer pressed power on button. After

some seconds, when Windows XP logo (with blue running bar) displayed in the screen, a sniff burnt came out from pc side. No smoke. Just something burnt. He immediately

powered off. So, now, I have again pc in my lab.
Here is where I have stopped. I would like your advice in this all trouble.

 

Some elements I will give you that might help you advice me on what to continue.

 

new PSU that I bought and installed on January:

 

https://www.corsair.com/ww/en/Power/vs-series-config/p/CP-9020049-NA

 

new VGA that I bought and installed on January:

 

http://www.sapphiretech.com/productdetial.asp?pid=6266479D-30D1-4810-9FBF-69B681F5909F&lang=eng

 

Also, have some other defective PSUs from other replacements. Working but in negative form.

 

Also, some other information that might help you, please ask me to answer.

 

So, what would be your opinion and advice for all this?

 

Thank you for your time!