Hi everyone,
I'm running out of ideas and would really appreciate some advice.
## PC Specs
- CPU: AMD Ryzen 7 9700X
- GPU: RTX 5070 Ti (currently removed for troubleshooting)
- Motherboard (original): ASUS TUF GAMING B650E-PLUS WIFI
- Motherboard (replacement): MSI MAG B850 TOMAHAWK MAX WIFI (brand new)
- Memory: Crucial DDR5-5600 32GB x2 (CP32G56C46U5.M8B1)
- SSD: WD_BLACK SN7100 2TB NVMe
- PSU: Corsair RM750x
- OS: Windows 11
## Background
I built this PC with all brand-new parts around October 2025.
During the first month, the system was a little unstable. Occasionally it wouldn't POST, but clearing CMOS always fixed it.
After that it became much more stable. For several months it worked almost perfectly, and POST failures became very rare (only once every few months).
Then in June 2026 it suddenly stopped POSTing completely.
## Current symptoms
- Power turns on normally.
- CPU cooler spins.
- No display.
- Cannot enter BIOS.
- Monitor shows "No Signal".
### ASUS motherboard
The DRAM debug LED stayed on.
I tried:
- CMOS clear
- BIOS FlashBack
- Each RAM stick individually in A2
- Integrated graphics (removed RTX 5070 Ti)
- Different monitor
- Different HDMI cable
No change.
## Replaced the motherboard
I assumed the ASUS motherboard had failed, so I bought a brand-new MSI MAG B850 TOMAHAWK MAX WIFI.
I reused the CPU, RAM, PSU and SSD.
On the MSI board I tried:
- CMOS clear
- Flash BIOS to the latest version (completed successfully and rebooted automatically)
- Both RAM sticks individually in A2
- Integrated graphics only
- Different monitor
Still no POST.
The MSI EZ Debug LEDs now show both:
- CPU (red)
- DRAM (yellow)
at the same time.
I have confirmed this multiple times.
## Question
At this point, what would you suspect next?
Would you suspect:
- CPU failure (possibly the integrated memory controller)?
- PSU?
- RAM?
- Something else?
Since the motherboard has already been replaced and the BIOS has been updated, I'm not sure what the next step should be.
Any ideas would be greatly appreciated.