Bought new gaming PC - 3 random crashes last night

Smooth-Op

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Hey guys!

I bought this PC and received it yesterday:
https://www.amazon.com/CYBERPOWERPC-GXIVR8020A4-Desktop-i5-7400-7200RPM/dp/B0747W15QL/ref=sr_1_1?ie=UTF8&qid=1518011547&sr=8-1&keywords=GXIVR8020A4

I bought it in used condition (still directly from Amazon) and was able to save about 100$. In retrospect maybe that wasn't such a great idea.

I installed my 500GB SSD and put windows on it then started updating and installing my stuff.
After being done, I ran a few benchmark without issues. I also played a few games at max settings and it went great for a few hours. However, the PC crashed 3 times while simply browsing on internet (Twitch, youtube, etc.). No BSOD, once it just froze and I had to hold the power button to manually close it and twice the screen went dark and it looked as if the PC was about to restart but it just didn't do anything and I also had to manually shut down the PC.

This can't be good. What do you thing it could be? Knowing I gamed a few hours and ran quite a few 3dMark benchmarks without issue - could it be a faulty ram stick? There are 2 sticks of 4GB in there.

I know I should probably return it especially since it was previously returned to Amazon by another buyer obviously but I spend like 4 hours on that PC setting up everything and installing my SSD with Windows etc. If I could find the issue with a reasonable certainty, I could contact CYBERPOWERPC and arrange for a replacement part.

What would you do?

Thanks!
 

Smooth-Op

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Hey guys!

I'm currently running memtest86. It's been running for about 45 minutes without errors.

The PSU is indeed another suspect (I doubt it's the CPU and the GPU since no crash occured during gaming or 3dMark).

How do you suggest I test the PSU?

And you seem to imply CyberPowerPC are known for faulty / cheap PSU?

Could the 500GB SSD I added to the build right away be too much for the PSU?
 


They use cheap cases, motherboards, ram and psu's to save every little bit of money they can.
Just open the case and tell us what psu it is. Usually it's a barely qualified unit from a garbage brand.
 

Smooth-Op

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Ok so I opened the PC and here's what I found:

MOBO : MSI B250M Bazooka
Memory : 2 x 4 GB DDR4 sticks from ADATA
PSU : 500W from ATNG

I had never heard of ATNG...
 

Smooth-Op

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So yeah I ram memtest86 for about 6 hours without issues and am now runnig Prime95. It's been about 1 hour without issues for the moment.

Here are some screenshot from HWMonitor:
https://ibb.co/hxaFmH

2 questions:

Is it normal for my CPU speed to fluctuate over it's normal speed of 3.0GHz (i5-7400)?
https://ibb.co/iZJ70c

Those readings are really weird... is it a problem or just bad readings cause they look way off...
https://ibb.co/cgEN0c
 

Smooth-Op

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I have not yet tried removing any memory sticks. Still both 4GB sticks are installed.

If I'm able to find a stress test that cause the crash, I will be able to start messing with the ram and make a diagnostic but since the PC went through 4 runs of memtest86 (4h) I don't think it's the ram at this point.