Games crashing with new custom PC, RAM likely the issue

I've had this problem for quite a while and nothing I have done has helped. I thought at first that my motherboard simply couldn't handle the RAM cards so I bought a different board but I get the same problem. Games will crash randomly for no foreseeable reason at inconsistent times, sometimes I can play a game for an hour but when I close it and start up another game then it won't run for five minutes or vice versa.

I have done many tests on different pieces of hardware and the only thing I've fully ruled out is the motherboard since the problem persists with different motherboards. I have had the task manager performance monitor open while playing games and when a game crashes both the RAM and CPU show no abnormalities, which does point to the GPU. I have done a memory test and no errors came up. I have tested with my old GPU and got the same problem which points away from the GPU being an issue. I used Hardware Monitor to check the temperatures of the CPU and the GPU neither of which exceeded normal temperatures whilst playing games. It seems that even playing older games like Hitman: Blood Money would also crash and even the Google Chrome browser locks up and restarts when trying to watch videos.

I went into my nearest PC parts shop to buy new RAM just to test if a different stick would work but unfortunately they were out of stock, I was told that the CPU has a maximum memory frequency and that my RAM might exceed that but after checking, I found that the RAM was well under the max frequency.

I have tried changing BIOS settings with the memory such as the X.M.P and also overclocking it to the CPU's max memory frequency but still got the same issue. I won't try updating the BIOS with this new motherboard because the first time I tried caused the motherboard to "get confused and not boot anything" (as some guy on Youtube phrased it) so when I got the replacement I tried a number of other solutions given to me by a friend who has built many PCs. I tried putting the RAM cards in each of the DIMM slots, checking for memory leaking and testing both sticks separately before updating the BIOS again and getting the same confused motherboard.

I have tried using one stick of RAM only and found no errors but the crashes are so very inconsistent that I'm still unsure. I am currently running with just one stick and plan to play games with the one stick for a few days to make absolutely sure that the problem may lie with the compatibility between the two sticks since Gigabyte claim that the motherboard can support up to four 4 sticks which of course makes sense with the four DIMM slots.

Lastly I want to mention that I spent full price for every component but the RAM, I thought I might save 20€ on buying the (2x4gb) Corsair Vengeance from a third party retailer on Amazon which (in my nervous Google searches) has a 70% chance of being a scam. Although the third party scam statistic may just be tabloid embellishment, I don't want to rule it out, particularly because the RAM is the cheapest and easiest thing to replace.

If anyone can help I would greatly appreciate it, I've been looking for a solution to this problem for months now and will rejoice once I get this PC working properly.

If it helps then here are my specs:
Motherboard - Gigabyte Gaming AB350-Gaming-CF
Processor - Ryzen 3 1200
Graphics Card - GTX 1050 2GB
RAM - Corsair Vengeance 8GB (2x4GB) 2400mhz
Hard Drive - WD Blue 1TB 7200RPM

Thanks in advance for the answers and a double thank you for enduring my lengthy post.