We came across a problem today at the shop. Someone had replaced the motherboard on their Sony Vaio laptop. The old motherboard had a problem so they bought a replacement on eBay. The replacement board worked, but, the unit would just boot up to “operating system not found”. No matter which key they pressed they could not get into the BIOS. They also tried using the assist button to no avail.
Since the board was previously used and the current hard drive was running Windows 7 Pro, we figured the previous owner likely ran Windows 8. Once Win8 is on a machine w/ UEFI, the BIOS must be accessed from Windows. In this case, booting the Vaio via “assist” will produce nothing and the user will not be able to get in to BIOS to change the settings.
To test this theory we took a hard drive which was lying around that had Windows 8 installed. We attached it to the machine and fired it up. Sure enough, instant Windows logo! Very neat. Of course, Windows wouldn’t load, but, we at least were able to discover the problem.
Possible solutions included repair the old motherboard, moving BIOS chip from the defective board to the replacement, or finding a compatible Windows 8 drive to move over.
If you have been running Windows 7 and install a used motherboard into your laptop with a UEFI BIOS and it will not discover a boot device, there is a good chance that the previous owner was running Windows 8.
Hopefully this will at least point someone in the right direction. Dealing with these BIOS set ups these days can be a real pain. It helps if you have a shop full of parts available to help you troubleshoot; if you don’t, well, good luck with all that.