I am getting desperate. Please help me

I’ve tried to make my setup work. I’ve been trying for more than 2 weeks now. I’ve already bought every single GPU/mobo/CPU/riser… etc that I could possibly need.

my rigs :
power: 1200W server PSU + pico psu
ram: some 8GB and some 4GB modules
MOBO: b360 b460 b450
CPU: athlon 200ge and celeron g3900.
GPU: EVGA + colorful + gigabyte + msi RTX 3070
storage: 120GB ssd

my problem is that I can not get ANY display from my rig… AT ALL. no display from the IGPU or the 3070 unless I plug only 1 GPU directly to the 16x PCIe slot and use the GPU’s output (and sometimes that does not work). I can not boot or even go into the bios. can someone please help me.

There is a whole mess of stuff you can try, which i’m sure you can tick off as I list them:
1- disconnect all peripherals including riser cables and video cards- start with only Mobo/CPU/RAM and integrated graphics.
2- If you get no display while connected to the IGPU of the motherboard- BIOS reset/CLEAR
3- Once your able to get IGPU display, update bios to latest version available from board manufacturer- may require USB stick formatted as Fat16/Fat32-
4- BIOS Settings- Use UEFI if possible, not legacy- tweaking the bios is going to be a huge amount of trial and error to get the right settings for your PCIE GPUS and riser combos- I’m sorry I’m not familiar with your boards.
5- Do not try to get them all working at once!!! Add in one at a time, get 1 GPU working and proceed to continue with each additional until you hit Eureka moment.
6- Basic hardware /software troubleshooting and patience will be your friend. Baby Steps!!

I really appreciate your response. I already did 1 - 4. I will definitely try 5 and 6. there is no video output but I will see what I can do. thanks