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New windows desktop can see boot drives only if video card installed ???


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Hi - a couple of months ago the MOBO in one of my wife's business's whitebox Desktop PCs finally died.  I took the machine to my local shop and asked them to build a new machine and use the existing SSD drive.  They did so, but they said that when they originally booted it, Windows (10) flagged a licensing issue, so they installed the video card from the old machine (a old nVIDIA GeForce 210) and it booted fine.  I was a little disappointed (I was intending to use the dual HDMI on the new Asus B560M-A AC MOBO) but we needed to get the PC back in service quickly so I went with it.  6 weeks later, things slowed down, and I wanted to verify the licensing issue. [I paid for all my windows licenses and so have been successfully been able to move them from machine to machine without issue.  Here, where the SSD was moved from one machine to another, it surprised me that they couldn't move it into the base machine but needed to move the video card with it.]


So, I opened up the machine and pulled the video card.  Long story short, here's what I observed.


a) Video card installed, monitor connected to video card:  Works great


b) Video card not-installed, OR Video card installed and video not connected to video card (connected directly to PC):  It stops at the BiOS and claims there are no bootable drives.  The BiOS lists the drives, but it no longer thinks any of the drives are bootable.


I called the store and asked them if they did anything special to the BiOS when they put the card in, they said no. (and in fact, the graphics selection menu in the BiOS is set to AUTO).  They did say they check the Sata controller, CSM, and secure boot settings, but not the graphics.  


I am baffled. 


Use the Video card,  Works great. 

Don't use the Video card, BiOS says "no Bootable drives". 


Any suggestions?




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Yes - it is an SSD formatted as MBR.   So you're saying the on-board -video- requires GPT?  I wonder why that would be the case.  However, that would definitely explain the issue.   I wonder if I can convert the drive safely using something like Boot-it....



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I think this is an Intel chipset thing. Probably any of the latest Intel CPUs with integrated video would behave this way.

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On 5/2/2022 at 8:09 AM, raymac46 said:

I think this is an Intel chipset thing. Probably any of the latest Intel CPUs with integrated video would behave this way.


I actually didn't realize that was even an issue. At work we only use HP Elitebook and their Z series. The Elitebooks are all high end intel with integrated graphics. Of course we only use UEFI (with secure boot)


My current laptop (HP Elitebook 830 G6) is only 2 years old and it has integrated intel video. Of course, I only use GPT/UEFI as well.




Intel Core i7-8565U Processor

Intel UHD Graphics 620



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  • 2 months later...



As a guess, the Nvidia GeForce 210 video card uses a BIOS-based option ROM to initialize, which was forcing the system's UEFI firmware to enable Compatibility Support Mode for BIOS firmware after POSTing.  When that was uninstalled and display was switched over to the on-board graphics from the ASUS PRIME B560M-A AC system board, the UEFI firmware no longer initialized CSM.  Again, just a guess on my part.


Aryeh Goretsky

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