Dear compound0321,

Greetings, this is ASRock TSD.

The Dr.Debug code 3F indicates the system is stuck at memory training process. (between code 01-54)

Please refer to user manual page33 about Dr. Debug detailed information.

 

Regarding this case, we provide some suggestions for you to verify:

 

1. Please refer to user manual page.26 to clear CMOS to verify. (Please shut down the AC power in advance)

2. Only install one stick memory to each DRAM slot by turns to verify.

3. If possible, please install other memory modules to verify.

Thanks!

All the best,

ASRock TSD

I have just purchased and built the X370 Professional Gaming with1800X and HyperX DDR4 3000 Mhz 2x8GB in Slots 2 and 4.

The issue is that the light simply flash red on the motherboard then the system will power off a few seconds and then restart again to again flash red. I hooked it up to a HDMI port on the GIGABYTE 1080 graphics card but there is no display output when powered on. 

The flashing red light continually does this for 30 seconds then seems to power up. On the motheboard it comes up with a code 3F however I could not find anything about it in the manually.

Can you shed some light what causing this, it not the motherboard as I replaced this same model recently and had the same error before, so it some other component. The only other component I ruled out is the Power supply.

If you can advice what could potentially be causing this. I can provide more information if required.