I have passed a couple of 1U servers to my dad, one is C2D based, another is 1st gen Core based.

He said recently Windows 10 gave error message say the graphics processor used on the mobo no longer supported.

Is that's true?

I can only remember the model of the C2D server, it's a Tyan Tank GT20 and it uses Xgi® volari z7 (xg20tm), 16MB video memory.

Googling didn't turn up anything (maybe I don't pay enough attention kua).

Is he using it as desktop PC where a monitor is plugged in directly to the server or is he accessing the server remotely from another PC/laptop/mobile device?

If he's using it as a desktop PC, just install a low profile GPU such as GT 1030 and your problem is solved
Also if he's using it as a desktop PC, just get him a new PC/laptop lar

If you can find 64bit drivers for XP, Vista, 7 or 8, you can still force install it.

I'm still using Radeon HD4850 by forcing Win10 to install 64bit drivers for Win7/8.

He using it as a desktop PC. I intend to get a low profile GPU but 1030 is a bit overkill la. But thinking about it he has about 10 PC/laptops. He has a 10th gen laptop, it is good enough for most of his purposes.

He just like older PCs because he said he needs to run some software from DOS era (max can run with WinXp) - that's why he maintains some of those PCs, even those he could just virtualize the DOS/XP PCs and run them there, so I don't get it why he maintains that many PCs.

I want to find out where (at which point in time and why) the mobo's on board graphics drivers are deprecated beginning with a certain version of Win 10.

Noted. Perhaps some used GT 730 would suffice
I just suggested GT 1030 because this is the lowest GPU that is still sold as new with manufacturers warranty
Probably because of security issue. Certain hardware manufacturer refuses to release hotfix for their older hardware especially something that is too ancient

Thus, Microsoft tag the hardware unsuitable for use with their updated OS

The same for old ThinkPads. Some in my collection cannot use W10 due to lack of drivers. Max also W7. As a result, these machines only suitable for running old and outdated apps. Web browsing, YouTube and more not possible.

Yeah, something in the region of RM50 to buy 2nd hand.

Ah... that makes sense. I was wondering why would Win10 suddenly just not work with these mobo graphics when it used to work, no fundamental change in Win10 sub-systems that would render drivers obsolete - the security issue is one probable reason why Win10 reject these hardware, to close a security loophole.

I saw similar problems with my C2D Thinkpad X61 - I took me a couple of years to find out that the issue was the built in WiFi card were causing bluescreens. I sold it off 2 yrs ago even though it was still good enough for my use case and went to a T430.

Glad I sold off the X61 as I have 3 more C2D laptops (that also have the bluescreens due to Wifi cards). Now on top of Wifi issue, will have iGPU not accepted by Win10, plus need to have SSD for them to work adequately with current version of Win 10.

All my Pentium M, CD and C2D ThinkPads with MiniPCI WiFi cards removed due to lack of drivers. Those B or G WiFi on MiniPCIe also removed because cannot connect to any modern A or N access points.

you can just get any mini pc with older-gen intel proc for cheap

How you found out? No information when I researched for it, until I used a wifi dongle and no bluescreens.

Open up and check the model / serial numbers.