What the..?!

[576869746568617]

Hell when did this start happening? or more importantly WHERE did you get this information? ..probably the same place that tell people that reversing the connection on their televisions will transmitt pictures to the waiting world..

Plug your Laptop into a generator and watch the time drift (of course this could have been due to me having a piece of crap laptop)

I know for a fact that at least one brand of laptop (which will remain nameless ...but i will say that they are made in South Africa and private labled to some of the larger comp mfgs/distros) uses input AC voltage to drive the clock. Talk about cheap.

Well most of this is BS.. the same battery that keeps the CMOS setting up also powers the RTC Chip (This little chip also has a Quartz xtal to help keep the beat in time..)

Most modern RTC IC's have a battery integrated into the IC. If affore mentioned battery is defective, it will resort to Main battery. Remeber that there are also 2 clocks on the machine...a hardware one (the RTC) and a software one called a timer-counter that runs independently of the Hardware clock. The timer-counter uses the CMOS battery, not the RTC chip.

The hardware clock (RTC) is based on the Motorola 146818 Real Time Clock Chip, or a functionally equivalent device. The software clock (timer-counter) is usually a device equivalent to an Intel 8254 timer-counter.

When the computer is turned off, it runs on batteries (CMOS battery for the Timer-Counter, and an integrated battery for the RTC). When the computer is turned back on, the software clock starts running again and sets itself (usually within 1 second) to the hardware clock. Although the two clocks are synchronized at start-up, they may run at very different rates and will probably gain or lose time relative to each other while the computer is running.

The hardware clock is updated once per second and cannot display fractions of a second. For this reason, it cannot be read or set within better than a second. The accuracy of the hardware clock is determined by the quality of its time base oscillator (typically a 32.768 kHz crystal). Most offer only marginal time keeping performance. They are sensitive to temperature and other factors and are often not calibrated at the factory. Even under the best conditions, these oscillators are not likely to be stable to better than 1 part per million (about 0.1 seconds per day). In actual operation, most hardware clocks seem to gain or lose time at a rate of about 1 to 15 seconds per day, with 5 or 6 seconds per day being "typical".

In contrast, in order to calculate time the timer-counter will typically generate an interrupt every 54.936 milliseconds, or about 18.206 times per second. Another routine counts the interrupt requests and generates a time-of-day clock that can be read or set by other software programs. For example, Windows uses the information from the software clock when it date-and-time stamps files. Its accuracy is limited by the stability of the interrupt requests. Any change in the interrupt request rate causes the clock to gain or lose time. If you leave your computer turned on for long periods, the software clock might be off by large amounts--perhaps a minute or more for every day that the computer was left turned on.

It's also possible for an ill-behaved software program to use the timer-counter for another purpose and change its interrupt rate. This could cause the clock to rapidly gain or lose time. Another problem with the software clock is that it cannot display all possible time-of-day values. The resolution of the clock is limited to the interval between interrupts, or about 55 milliseconds as stated earlier. Only times that are even multiples of this interval can be displayed. For example, 00:00:01.00 could never be displayed by the software clock. The closest possible values it can display are 00:00:00.98 and 00:00:01.04.

IF the problem is the timer-counter (software) clock drifting while the power is running...replacing the CMOS battery would not fix that. When the system boots, the timer-counter sets to the time of the RTC. So it would appear that the root problem is the RTC, and replacing the CMOS battery won't do squat to fix that IF the RTC runs on an integrated battery on the IC. At boot, the two clocks will sync and the software clock will set to the erroneus time given it by the RTC. If, however, it's a RTC that shares the CMOS battery with the timer-counter (which is certainly possible), then yes, a CMOS battery replacement WOULD fix it. There are a plethora of reasons for a clock to run slow while the laptop is running...but if it drifts when it's off there are only a few.

By all means replace the CMOS battery, I wasn't trying to say that this shouldn't be tried. The laptop ones a re a little bit more expensive than the standard 3v 2032's used on desktops, but it's by far the cheapest thing to try.

Another thought...has he checked to see what the BIOS time is? Also, did his laptop need a BIOS update to handle the new DST change?

As he has said that the system forgets his power settings, I'm thinking that it's the Windows ACPI. As I said earlier the ACPI specifies when components should be active or inactive to conserve battery power. Conflicts between time values in the BIOS and Windows setting can cause irregular computer clock operation. This is a known bug on several HP notebooks (although not sure if your particular model is one of these).

Well most of this is BS..

I never said it wasn't...I'm surely not an expert by any stretch

Hell when did this start happening?

Probably about the same time I got abducted by aliens :S


*********************************************************
--EDIT: After looking at the system maintenance and service guide for your laptop it is very clear that your RTC does indeed have its own battery seperate from the CMOS battery...however it is an external replaceable battery, HP part number 431436-001. Cheapest one I can find is about $23.00 USD. (http://www.jpcparts.com/page/search2...ber=431436-001)

It appears to be replaceable without complete disassembly of the laptop- remove the memory expansion door on the bottom of the laptop and any DIMM(s) in there and you'll see it...just unplug the little dongle coming from it from the system board and it should come right out - too easy.

Download this file for future reference - HP Pavilion dv6000 notebook Maintenance and Service Guide (http://h10032.www1.hp.com/ctg/Manual/c01035677.pdf)

**********************************************************