Vostro 3910 RAM upgrade won't work and Dell support got no clue how to help you

I am trying to simply upgrade Vostro 3910 ram to 2x 16GB

I tried:

Corsair CMK32GX4M2Z3600C18 VENGEANCE LPX 32GB (2 x 16GB) DDR4 DRAM 3600MHz C18 AMD Ryzen Memory Kit - Black

I know it's 3600Mhz but all the knowledge online says that it will work but simply to the 3200 capacity.

I contacted so called Dell technical support that the best is trained to do is to copy and paste spec from their website and claimed that 3200 should solve the problem.

So I ordered another set of RAM, this time 3200Mgz:

CORSAIR CMK32GX4M2E3200C16 VENGEANCE LPX 32GB (2 x 16GB) DDR4 3200 (PC4-25600) C16 1.35V Desktop Memory - Black

Same issue, it doesn't boot, even with one slot or even with one old one and one new one.

The power button only blinks with white and then orange light.

Another two conversation with first and probably second line/level of support didn't have a clue as well, suggesting that maybe consequent 4 pieces of RAM were faulty.

I just want to know what RAM do I need to buy for this machine without spending the suggested £300 RAM offered me in the link while all the above options cost max £80  with thousands of happy customers on Amazon.

I suspect the voltage is weak on this motherboard but could someone shed some light?