Startech PEX2S553 PCIe Card will non install on HP EliteDesk G1 running Windows 10 Pro 64-bit

[RottenBoot]

I cannot get the Windows 10 Pro 64-Bit, 21H2, Build 19044.1415 to properly install a Startech PEX2S553LP PCIe serial card.  The Device Manager gives:  "This device is not working properly because Windows cannot load the drivers required for this device. (Code 31).  Object Name not found."  I followed the directions given at:  https://www.startech.com/en-us/faq/asix-serial-install-advanced-windows-v7810 to no avail.  Initially, the EliteDesk saw the card but then upon subsequent restarts, the PCIe card disappeared.  I reinstalled it using the proper driver recommended by Startech as shown in the link above, but the card will not work.  The card does not disappear now, but it still will not work. I see another user had a problem like this with a Startech card on a G4, but it looks to me like that user did not find a solution.

[DGroves]

uninstall current driver, then reboot and try the latest driver from the maker of the serial chip used on the card

https://www.asix.com.tw/en/support/download

select interface IC's , then MCX99xx  where xx is the last two numbers on the chip used on your card (should be 22 i think)

[SDH]

Many of the HP families have multiple PCs included.  It helps to know officially what your form factor is... SFF USDT DM TWR CMT and on and on.  I'm guessing that you have either a SFF or TWR version.  The SFF takes a low profile backplane insert and the TWR takes the full height one.

For many years HP has included a proprietary motherboard header for the "2nd Serial Port" (even if the rear of the computer did not have even one).  That interface uses a special HP adapter that plugs into the motherboard header and also is added to your backplane via a ribbon cable.  Those are cheap, used, off eBay... about $10,00 USD and there are a bunch of these with different part numbers from HP over the years.  For us they all have performed exactly the same regardless of part numbers over the years.

Serial traffic is so slow you don't need to waste a PCIe or PCI slot on a dedicated PCIe card when these are HP engineered, so cheap, work so reliably, and need no drivers because they are plug and play with XP/W7/W8.x/W10/W11.  This is one of those hidden treasures present on many HP motherboards.  Well, a small hidden treasure...    We need to use these for some software-unlocking dongles and for control communication with some of our Falcon UPS hardware.

In my experience they all have worked equally well, and some on eBay right now come from parting out Z440/Z640 workstations.  Those all had their PCB printed with date of manufacture "2004".  Same PCB for years. 

Just make sure you receive the special flat cable that goes from the motherboard header to the backplane adapter PCB, and that you get the correct height backplane adapter metal plate (the kits came with both sizes originally).  Be clear with the seller what height you need.  The option kit and spares part number I've added to the pic below will get you started and you can use eBay search for the earlier and later part numbers which result in same function regardless: