Corrupted BIOS – This Worked For Me

I bought a Vostro 3900G mini tower (Core i5-4460 3.2 GHz) back in 2014. It’s the best Dell I ever owned.

It basically ran fine until 2017 when Dell replaced the PSU, system board and power switch. A couple of years later the new PSU failed. I replaced the PSU with a Seasonic Focus GM-550; the graphic card with an MSI NVIDIA GeForce GTX 1050Ti; and the HDD with a WD 250GB SSD.

But I still experienced unexplained slow POST, Windows Explorer freezes, CPU fan speed surges, high CPU usage, etc. Windows Defender offline scan and Malwarebytes didn’t detect anything. Reflashing the A16 BIOS in UEFI mode (within Windows and from DOS) and clean reinstalls of Windows 10 (English) didn’t achieve anything. Dell Diagnostics, Memtest86, etc. didn’t show anything unusual.

I was beginning to think that the system board had been damaged when the PSU failed. Nevertheless, on a hunch, I decided to reflash the BIOS in Legacy mode from DOS. Wow! For the first time a strange popup appeared in Japanese. I shutdown the PC and reflashed the A16 BIOS again. This time there was no strange popup.
The BIOS update reported that the ME version is same or lower.

In BIOS setup I changed Boot to UEFI and used the PC for about a week. It was much better but not quite right. So, I reflashed the original A13 BIOS in Legacy mode (same ME version is same or lower message) and then updated to A16 in Legacy mode. Reset BIOS setup Power option to UEFI mode and installed the Dell Security Advisory.

All the previous problems are gone. I hope this helps someone else.