Build Advice SOS big problem fresh built by expert pc no OC

[yolor3stis]

just got me a pc built it but some stuff didnt work so took it to a technician
specs:
ryzen 2600x
rtx 2060 gigabyte
6 fans total 3 bitfenix spectre white
and 3 corsair ll120 white
asus x370
vengance rgb pro
aio cpu cooler h100x with faster than included fans installed on radiator
so the expet built it (here ill mention that the pcie cable that came included had 2 pairs of connection things so it was maby for sli or maby for gpus that require double cable and we the second one off where it split but both the expert and a technician i know said theres no problem) i took it home all good. but within like not even 5 days
i was playing brawlhalla, a 2d platform game (not intensive in any way ).
and the monitor suddenly went black
like it checked and couldnt find signal from the pc. the fans custom rgb that i set up went back to the default rainbow and so did ram keyboard and mouse motherboard rgb i believe stayed the same also the front power button was still lit up but doesnt work when that happens i have to close the psu. i hoped it wouldnt happen again
and i kept on using the pc . happened again after 2 days. same thing as i remember it . same after another 2. and i said if it happens again ill give it back to the technician and well figure it out. didnt happen for i believe over a week but here i am so you know where this is going just happened again.monitor closes first fans keep spinning but eventually their leds turn off ram actually kept the custom software based rgb settings motherboard as well and power button same deal . called the guy and he said ill have to first try the uncut cable and if i get the same problem again ill have to remove and replace everything one by one to see. i REALLY need some insight on this since the gpu store took 2.5 months to deliver and i really dont wanna have to deal with them again if i dont have to so that basically. forgot to mention that the initial problem when i was building it myself was that while only a fan was missing to complete suddenly all the conections stopped working but i believe the power button worked that time

 

[yolor3stis]

also memory is 1tb ssd from sandisk and 1 tb hdd from seagate idk which one my stuff is on since their both named the same. all temps under 35 while idle or consuming media and never at any point have they hit over 65 for any component

 

[popatim]

That is Storage my friend.
Memory is your ram, which you left off of your list along with the Power Supply (PSU) info which may be the issue. What is it's make and model#

 

[yolor3stis]

Ram is 16 gb (2
X 8)
And psu corsair cx650

 

[popatim]

Did you , or the expert, enable XMP for the Ram in your bios?

You don't list which exact ram you have but they may need a little more voltage to work properly.

Also, run GPU-z and make sure yours isn't a fake. 2.5 months to get a common card seems way out of the ordinary, like it came by rowboat from china...
https://www.tomshardware.com/news/gpu-z-update-detect-fake-nvidia-graphics-cards,37934.html

 

[yolor3stis]

Did you , or the expert, enable XMP for the Ram in your bios?

You don't list which exact ram you have but they may need a little more voltage to work properly.

Also, run GPU-z and make sure yours isn't a fake. 2.5 months to get a common card seems way out of the ordinary, like it came by rowboat from china...
https://www.tomshardware.com/news/gpu-z-update-detect-fake-nvidia-graphics-cards,37934.html

Ill tell him to try enable the ram thing which I don't know how to do the graphics card was bought from an ok rated eshop they were late to get it because there was a shortage of the certain gpu and ram is corsair vengame rgb pro 2x8 gb which I said but ok