BIOS更新失败，CPU未启动
BIOS更新失败，CPU未启动
You're looking to upgrade your system with a prime h370-plus/csm MOBO for an i5-9400, which is Gen 8 compatible. Since you don't have a Gen 8 CPU, you'll need to flash the BIOS. You can flash the BIOS either with or without the CPU inside, depending on your motherboard's support for that method.
He’s moving and doesn’t know how to set up a computer. His current machine is a Gen 3 i7 and it’s not working well. He’s trying to make the most of what he has right now.
You'll likely have to refresh the BIOS using your current CPU. This typically means placing the BIOS file on a USB drive, restarting into BIOS mode, and employing an update tool to pick the file from the USB. A CPU must be present to access the BIOS and complete this process. It's a good idea to look for instructions tailored to your motherboard model.
He seems to be aiming for an i5-9400 at the best price available right now. It’s unlikely he can afford both a CPU and a motherboard for an AMD upgrade while keeping enough funds for a superior AMD CPU option.