Are all of the components brand new?
What error code are getting?
Try posting with only one stick of memory installed, switch different slots.
Did you remove the CPU to check the socket for bent or broken pins?
Double check your PSU cable connections to the board.
Try posting with all USB and all drives disconnected.
You might even try removing your 980Ti and attempt posting with the iGPU.
Intel i9 10850K@ 5.3GHz
ASUS ROG Strix Z490-E
Corsair H115i Pro XT
G.Skill TridentZ@ 3600MHz CL14 2x16GB
EVGA RTX 3090 Ti FWT3 Ultra
OS: WD Black SN850 1TB NVMe M.2
Storage: WD Blue SN550 2TB NVMe M.2
EVGA SuperNova 1200 P2
ASUS ROG Strix Helios GX601