Question Dead pc after GPU upgrade? CPU and DRAM led, tried everything?

[klijakub]

Hello,
I have: i7 9700K / MSI Tomahawk z390 / 32GB RAM HyperX / SilentumPC 750 W Gold / GTX 1060 6GB
I upgraded GPU yesterday to the new RTX 3080 12GB, and I added one new SSD SATA 1TB
Plugged in everything and started the PC.
Nothing is displayed on the screen; PC rebooted 3-4 times, and DRAM and CPU easy debug led were blinking

Ok, so I removed the new GPU, put the old one, removed the new SSD, and restart the PC - the same, no display, some restarts e.t.c. DRAM led

So I removed everything, left with CPU and one RAM stick - still the same DRAM led
I've put one more RAM stick 2x8GB - something changed - there was no DRAM LED, PC restared 3 times and no display (I was trying to connect 2 different monitors, to gtx, and to the Motherboard)

Bios reset - done by pulling out the battery

Anything more to try?
I have no idea what else to do now;/

 

[rgd1101]

full system spec? include brand and model of the psu

 

[klijakub]

SilentiumPC Supremo FM2 750W 80 Plus Gold

And noticed one very strange thing.
On 2 sticks 2x8GB ram there's no DRAM led error on MB (but still no display)

If I put just one - there is DRAM error (still no display)

If I put 2-3-4 ram sticks - dram error
there's no error only on 2 sticks (2nd and 4th slot)