Is a BIOS system specific, or can I update it via 3rd party utility?

TL:DR - BOLDED

I've never really bothered learning much about updating the BIOS, because I've needed to up to this point. Now, I have two laptops where the manufacturer does NOT supply BIOS updates (Compal KHLB2, Clevo W230SS). I had always assumed that a BIOS is system specific, and that if the manufacturer does not have an update, one does not exist. However, after messing around with CPU-z, there is a BIOS update utility where I can what I assume to be a generic BIOS update.

What I'm interested in knowing is should a trust a 3rd party BIOS update utility since the manufacturers of my laptops don't offer BIOS updates directly? Because both these laptops seem to have issues that a BIOS update might fix

As for issues, if you're curious, is that the Compal laptop takes forever to POST - it can literally boot to the Windows desktop from the boot manager faster than it can POST. As for my Clevo, the headphone jack seems to not want to output sound every once in a while - this has happened on both Windows 7 and Windows 8.1, with and without the Realtek driver. I couldn't find a solution to the problem outside of a hard reboot. Even a proper reboot doesn't fix it - it has to be a hard shut off to restore my headphone jack.

Id be very cautious of 3rd party BIOS updates unless there is already a good number of successful test cases. I run a modded BIOS on my old R61 thinkpad with no issues but I read up heaps on it before flashing.

First email the manufacturer asking if there is a direct BIOS update available, who knows maybe they cbf'd updating their site or its still in the works. Id sooner trust a vendor BIOS over anything else.

Otherwise find a forum thread with details about the BIOS/laptop you intend to flash. Triple check everything. Its a right pain in the arse to source new BIOS rom chips especially for laptops if shit hits the fan and the flashed BIOS is a dud.