System clock

Discussion in 'Hardware' started by mgookin, Nov 25, 2008.

  1. Does anyone know if the Windows clock is running off the BIOS clock or independently?
  2. Is the "system" clock run from the BIOS? Hadn't thought about that.

    If you've got some kind of real-time data or trading connection, your system clock should be set to the web clock at least once per day... and the web clock is set by the official standards clock...
  3. 377OHMS


    There is the pc clock which returns absolute time fairly inaccurately and there is the high-resolution CPU counter which is accurate for relative time measurements to a few microseconds.
  4. I use Trading Technologies TT_Trader. The time displayed is my system time according to TT. They tell us not to use "auto-update" in our clock and not to change the clock with the application running.

    I think I'll be able to find out if they are synch'd by looking in the BIOS clock AMC today. I'll let y'all know what I find.
  5. promagma


    The system clock copies the BIOS clock at bootup, but then uses a timer interrupt to calculate time going forward, which can drift over time. Windows internet time sync is no help and should be turned off (like they say it causes time jumps and confuses the TT software). An easy solution is to run a program like Neutron that will quickly sync to an atomic clock every bootup. A better solution is to install NTP, which compensates for the drift on a real time basis.
  6. Are you sure the system clock copies the BIOS clock and not vice versa? Here's my experience...

    I was on a trail version of WinXP X64 and it expired about a month ago, so in lieu of installing the new version "over" the temp trial version, I installed the new version on a whole new out of the box HDD. I must have blown through the part where they ask you to check the time (I typically bang through all the default settings when I install something). About 2 days in to trading I realize the system clock is off by a month or so. So I go to Control Panel/ Date Time and fix it.

    Here we are a month or more later and it's off by about 8 seconds (my baseline could have been off by the 8 seconds when I sync'd it a month ago).

    Today I checked the system clock relative to the system clock on another system in this room. I then went to BIOS and checked that clock. The BIOS clock is in sync with the system clock.

    This tells me that the BIOS clock was a month off when I installed the OS and it was corrected by me fixing the date/ time a month ago.

    As for the 8 seconds, I'll get that later. But the logic tells me the BIOS clock is being manipulated by human intervention with the system clock in the OS. If this is true, changing only the system clock in the OS should put me in good shape.

    But if the BIOS clock is manipulating the system clock, then I need to replace the battery in the mobo (mobo is 1 year old).

    Make sense?
  7. promagma



    It makes sense ... when you fix the time in Windows, it does fix the BIOS clock to match. Since you are only losing a few seconds, the BIOS clock is doing a fair job at keeping the right time for when you bootup.

    Or, if the BIOS clock is drifting badly, but you set Windows to periodically get the time off the internet, you might never notice.
  8. Thanks pro... That makes sense to me. I see my windows clock drifing a couple seconds per week and for the money I invested in that machine, I think that's a bit much. From what I have gathered here I think I can just synch the windows clock once per week or so and be good to go. I am ok with a few seconds off (it has no bearing on my trades as there is zero latency) I only want to know when news is coming. Thanks again for the info; this site is great having persons with common interests with varying expertise. United we prevail.