[Macboatmaster]

This

but I saw that there were only two cores operating in my task manager.

MAY suggest that in msconfig CPU has been configured incorrectly
Check the setting in msconfig:
1) Press Windows key + R
2) Type msconfig
3) Click Boot
4) Click the Advanced Options button
5) Make sure that there is no check for the box "Number of processors"
OR indeed for Max Memory
Both those should be left UNCHECKED

 

[Macboatmaster]

Flavallee
I agree with you, but the crux of the issue appears to have been

I don't know how I did that, but I saw that there were only two cores operating in my task manager. When I switched on the other two, everything was back to normal. I appreciate your reply.

which as I said MAY have suggested that the sometimes common error of configuring number of processors in msconfig had been made
as per this thread on microsoft
Task Manager is only showing only half of my cores and logical - Microsoft Community
where it was - just that cause

hi, thinks for your advice, but i fixed the issue by unchecking number of processors in system configuration. Thank you all for your help

 

[Macboatmaster]

I agree - well spotted
I think it is actually an HP

HP 6200 SFF

HP Compaq 6200 Pro Small Form Factor PC - Specifications | HP® Support

but the same principle certainly applies.

 

[Macboatmaster]

Phill
Cheers

As I said previously - on my first reply

MAY suggest that in msconfig CPU has been configured incorrectly
Check the setting in msconfig:

after seeing this on post 3.

I don't know how I did that, but I saw that there were only two cores operating in my task manager. When I switched on the other two, everything was back to normal. I appreciate your reply.

However the response to my suggestion was

Done it ,it helped ,thank you

so we do not really know if the CPU operating on two cores was the result of an incorrect setting in msconfig, or a automated partial shut down of the CPU due to power issues, heat or whatever.

Until and IF Sj07 comes back to his discussion, it is a matter of pure conjecture.

That said I wish to repeat that I agree with you regarding the card and the PSU and as I said with Flavallee

Best wishes
Macboatmaster