Require help on unknown boot issue

[Boleyn]

Hi all.

A few hours ago I turned my PC on and it booted into windows as it always does.

I started watching a video then left the room and when I returned the PC was still on but not visible on my TV which it's connected too.

I restarted the PC and it did the same, turned on but not visible on the TV.

I restarted again and this time it turned itself off after a few seconds.

Multiple attempts later and it either stays on for a few seconds then turns off or stays on for several minutes before turning off.

I have replaced the GPU but that hasn't worked.

I am given no indication from the motherboard via beeps or lights to give me any further information and I cannot access the BIOS.

Can anyone here offer some help?

Thank you.

 

[Boleyn]

Built in late August 2024, everything brand new.

Nothing has changed since then and its been working perfectly until today.

I have:

ASUS ROG Strix B650E-F Gaming WiFi​

AMD 7800X3D​

G.Skill Trident Z5 Neo EXPO RGB 64GB​

TUF Gaming 850W Gold PSU​

WD_BLACK SN850X 1TB SSD​

Thank you

 

[Boleyn]

Cleared CMOS, tried icpu, no led's lit at all and changed cables and no change.

It just keeps turning off after either a few seconds or several minutes with no indication of what's wrong, incredibly frustrating

 

[Boleyn]

Thermalright Phantom Spirit 120 SE ARGB Dual Tower CPU Cooler - 120mm.

Tried the 1 stick of ram, no joy and all cables are secure.

That leaves the cpu, motherboard or psu.

All three as previously mentioned were brand new, bought in August 2024 and have worked flawlessly since then until today with no tinkering since, it's also not overclocked.

No idea why it just stopped, nothings changed from yesterday to today.