Welcome to the forums, newcomer!
We're going to need a little more information. Please list the specs to your build like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
While on the single RTX3090, can you get into BIOS and see what BIOS version you're on at the time of writing? Include the make and model of the PSU, apart from the wattage and include the age of the PSU if it's been brought over from a prior build.
While it on the single RTX 3090 it work fine. But While I Plug second GPU it stuck at D4 or 94 code. and I expect 4 RTX 3090 for this mother board .
This is my SYS SPECS,
OS: Window 10 21h1
CPU: Ryzen Threadripper Pro 3955WX
MEM: 32GB - 128 GB DRR4 2Rx4 PC4 2400T
MOBO: Asus Pro WS WRX80E-SAGE SE WIFI
GPU: 2 - 4 Nvidia RTX 3090 Gigabyte
SSD: 1x 970 EVO NVMe® M.2 SSD 1TB, 1x Samsung 850 PRO 512GB 2.5" SATA SSD
PSU: Super Flower Leadex Platinum SF-2000F14HP 2000W