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Losing track of time: Fixing computer time and clock problems

Question:

Why does my computer keep gaining minutes every day? If I set it back to the right time in the morning, by afternoon it's gained 5 minutes.

Answer:

Older cars lose oil. One of my past cars, a lovely 1999 Saturn SC2, started to consume oil after it turned 60,000 miles. However, there wasn't much I could do about it. The dealership told me that as a car gets older, it's expected to burn miles. And for an older Saturn, burning one quart of oil every thousand miles was considered "acceptable". I couldn't argue with the dealership, so I just shut up and continued checking and filling the oil as needed.

Computer clocks used to be like that. A few minutes drifting every month was arguably accurate. But these days, we don't have to put up with messed up clocks. If your computer's clock is noticeably gaining or losing time, one of several things could be happening. Here's how to handle each:

1) Are you logging on to a network with a server?

On a network with a server, you'll often have time synchronization. Time sync means that the server (who manages and keeps track of all computers connecting to it) needs to be able to accurately monitor, start and stop events on its client PCs. To do this, it needs accurate timekeeping. To enforce this, it sets the client PC clocks to match its own every time you log in. In the question above, this is the first answer I'd give: If you're logging on to a network, it doesn't matter if you set your PC's clock - it may be overridden daily by the server time synchronization policy.

2) Are you losing the PC time completely?

If your computer's clock is way off, or if the time is really different every time you boot, your CMOS battery may be dying. The CMOS battery is a small battery inside your PC that remembers important information when you turn the computer off. If your PC "forgets" the time every time you unplug your PC, that battery may be dead. Replace the battery with a new one. This is a fairly easy process if you've ever opened your PC before: You should be able to find the CMOS battery on your PC's mainboard. Just carefully pry it out of its mount and press in a new one. The CMOS battery looks like a large watch battery, about the diameter of a dime or quarter.

3) Is the time gradually changing (minutes per week)?

If your computer's clock is gaining or losing minutes at a slow rate, say a couple minutes a week, you just may have a poorly designed or slightly faulty CMOS. No problem, though. For computers not connected to a network with a server, Windows XP allows you to synchronize your clock over the Internet. This process is Windows "time synchronization", and can be performed manually. If you don't run it manually, it will automatically synchronize your computer's clock once a week. (For those running a non-Microsoft firewall: For Windows time synchronization to work, you need to allow "NTP" traffic.)

To enable time synchronization, go to Start Menu -> Control Panel -> Date and Time, and click the "Internet Time" tab on the Date and Time window. Click "Automatically synchronize with an Internet time server" and time synchronization will be turned on. If you do not see the "Internet Time" tab, then your computer is either part of a Windows network "domain" (you log on to a server-controlled, time-controlled network), or you have an older version of Windows: Anything before Windows XP doesn't support this.