Date keeping issue windows 2000

[Dimitris_4]

Hello. I would like to have your advice. I want to buy an old desktop with windows 2000. This desktop pc controls an opthalmology eye tomographer which is quite expensive.
The problem is that each time the pc starts up it cannot show the right date but shows the date the pc had when it was shut down. So if I shut down today tomorrow it will show today date etc.
The seller corrects the date each time from windows , not the BIOS. He has also left the pc plugged in but shut down and it still keeps loosing the date.
I have read threads about the CMOS battery issue but the problem is that in this pc the cmos is soldered to the motherboard and is not easy to change.
So do you think that this might be another problem? Maybe better not to buy?
Bios at start up does not show cmos battery low voltage alert..

 

[kanewolf]

Many computers use an eternal source from the network to sync the time at boot. Is this PC on a network with access to the internet? If so the time sync needs to be checked in Windows.

 

[Dimitris_4]

The computer must have an internet card but is not currently connected to the network. It is on a retailer shop.