RTC Battery is low or CMOS checksum is inconsistent


When you turn on your Toshiba laptop computer you get the following message:
“RTC Battery is low or CMOS checksum is inconsistent”.


  1. Press F1. You will be taken to the BIOS menu.
  2. Press the End key. If this doesn’t work then look for the words “Save Settings” at the bottom of the screen. The key you need to press will be to the left of it.


  1. I have the same message when I turn on the laptop – but, it won’t allow me to press the F1 Key – any suggestions?

  2. From what I read on other sites, plugging in an external usb keyboard will allow you to press the F1 button and set the date and time. Then it will load the operating system like normal. Try this.

  3. I have the same problem as stated above.I hit F1 and enter the Cmos set up.I already downloaded a CD with a a new Cmos update.I set up the priority boot to CD and saved the settings by hit END.However nothing happened and it again go back originally to message RTC battery is low or CMOS checksum is inconsistent.I am quite frustrated .Any help I will greatly appreciated.My Labtop computer is Toshiba S300M-EZ2401

  4. Pls i need help. I have a new morden laptop Toshiba satlite (touch screen). I powered it one day and it went down automatically, i had to on it and it goes off after a second, i left it for about a month now if u one it, it showes RTC battry is low press f2 to set time and date, bt i hit f2 like mad bt still no responce and d system nw goes oss after like a minite. Pls what do i do? This laptop is just 5months old am in Nigeria bt d laptop ws bought in Washigton. This my number 08064357667

    1. Hello Francis,

      Thank you for commenting but if you have a new computer you will need to contact your local authorised Toshiba repair centre to arrange a warranty repair.
      Hope this helps.


  5. I had a RTC battery is low msg on my Toshiba c850 laptop. Trawling other forums only showed how to change the battery which I had done anyway…The problem was I could not get past that RTC msg at all – UNTIL I READ VINCENTS COMMENTS – Much thanks from more heartache.. I added the keyboard as suggested which got me past the msg in question and was able to update the bios and hence go into my o/s. For some reason the laptop will not respond to it’s own keyboard until an outside influence is added… Scary.. Thanks again Vincent.

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