How to update BIOS on computer that won't boot up?

My son is building his first PC with my assistance, and we're running into an issue where the PC will not boot up into POST. No signal on monitor, no beeps or POST codes. CPU fan and system fans are spinning up as expected, video card shows a power light on. Also tried it without the video card plugged in, using just the native video - no change.

We confirmed that the CPU is supported by the motherboard, but the manufacturer states that it is only supported with a BIOS update. Problem is, we cannot get to the BIOS screens, or even to the point where it is attempting to boot from a drive or device.

Given that we cannot get past the POST stage, how can we update the BIOS on this system so that the CPU is supported?

UPDATE: The motherboard appears to be a Biostar Biostar TB250-BTC+ if that helps. CPU in question is an Intel Core i7 7700K

SOLVED: Ultimately could not get the BIOS to update even using Intel's flash utility on a thumb drive. Ended up returning the CPU and getting a replacement (exact same one), second one booted right up. So I'm guessing we just had a faulty processor.

4 Answers

If you are using an AMD platform, fill out a warranty request for 'boot kit required'. They will send you a cheap APU that can be used to update your bios.

If you are using an Intel platform, some Intel motherboards have a way to update bios without the CPU. Check your manual. On Gigabyte boards, the feature is called "Qflash Plus". On Asus boards, the feature is "USB BIOS Flashback".

If this doesn't work out for you, you can order a compatible processor and return it after doing the update. Some retailers have a formal process for doing this so you don't have to renege them.

In addition to Andy's excellent info, MSI motherboards also have a BIOS Flashback button on the rear panel (so you don't have to open up the case) that enables updating the BIOS with an FAT32 formatted USB drive. I have a MEG Z390 ACE motherboard. The instructions are:

1. Connect power supply to CPU_PWR1, CPU_PWR2 and ATX_PWR1. (No other components are necessary but power supply.)
   
2. Plug the USB flash drive that contains the MSI.ROM file into the BIOS FLASHBACK+ port on rear I/O panel.
   
3. Press the BIOS FLASHBACK+ button to flash BIOS, and the light of BIOS FLASHBACK+ button starts flashing.
   
4. After the flashing BIOS process is 100% completed, the button light would stop flashing and would be off simultaneously.
   

These instructions were copied and pasted from the PDF of the user's manual.

I imagine the instructions are pretty close to identical for other newer MSI boards, as well.

Assembling a PC from parts is fun and educational, but sometimes also slow and frustrating, when you get stuck on things like this. One solution is to buy, or borrow, the cheapest compatible cpu you can find, and temporarily replace your real cpu, to do the update.

There's an 8 pin IC in a socket in the corner, but I can't find a picture where I could read its type. Can you read it?

I have a theory it is the flash (or possibly eeprom) chip that holds the BIOS firmware. If it's a common chip, and you have a very basic knowledge of electronics, with a simple hardware you can flash it (after doing a backup of course). You'll need a working computer, a flash programmer (or an arduino, e.g. a nano is around $2), some wire, and of course the newer firmware.