I have to power on my laptop twice?

[ARom]

Turns out it was the operating system. The computer came with Vista Business 32bit but I downgraded to a spare copy of Windows XP I had lying around. I just installed Vista Business to sell the computer (corresponding to the sticker on the bottom) and the problem stopped (i was wrong)

[TANWare]

My P79xx has a similar issue. My Mushkin SSD drive when cold will not initiallize. Sometimes it can take 3-4 power ups to get it going. Sometimes it will just power up with no issue at all.

[ARom]

According to the Service Manual and google it's a standard CR2032 battery. Brand isn't important.

Now that I think of it, if your BIOS settings aren't lost when you unplug the power and the battery, then there's maybe some other issue.

I don't know if I'm getting ahead of myself yet but it looks like it was the CMOS (CR2032) battery which was almost dead. HP calls it the RTC battery in their service manual.

I replaced the CMOS battery and 'Shut down' from the start menu now works properly booting up but 'Restart' does not

[ARom]

My P79xx has a similar issue. My Mushkin SSD drive when cold will not initiallize. Sometimes it can take 3-4 power ups to get it going. Sometimes it will just power up with no issue at all.

Try replacing the CMOS battery

[Kawasaki268F]

Try replacing the CMOS battery

hmm never heard of that or where to find it but I will look it up and maybe do that

[halladayrules]

Normally, if the CMOS battery is faulty the user should have at one point or another reset the date and time his or her machine. User should have also noticed a "Certificate has expired or is not yet valid" when browsing secure HTTP sites such as online banking or when logging onto Facebook/Yahoo etc. If you've had to do that at all recently - replace the CMOS battery.

Sometimes laptops can heat up very quickly and cause the thin pieces of wiring holding the capacitors to break resulting in an uneven current which can disrupt the electrical flow resulting in power outage/random blue screens. First check the capacitors on the laptop itself for leaking or "bulging" capacitors. Also check for any capacitors that may be disloged as a result of what I was mentioning above.

Symptoms of bad capacitor - System memory hard faults when loading applications. When surfing web the computer will instantly shut its off and turn back on. One good one I have discovered myself was that Windows will refuse to install even if you are booting it from a fool proof USB stick. If you have tried to install Windows from a known good USB stick (that you've tested on another machine to proof it works) and the OS will not install, then you have a bad capacitor FOR SURE.

[ARom]

I don't know if I'm getting ahead of myself yet but it looks like it was the CMOS (CR2032) battery which was almost dead. HP calls it the RTC battery in their service manual.

I replaced the CMOS battery and 'Shut down' from the start menu now works properly booting up but 'Restart' does not

... changing the CMOS battery did not fix the issue over time. But I wonder why it fixed it for many hours.

Could be a bad capacitor. Power bricks and computer power circuitry makes use of capacitors to regulate voltage and current. Modulation makes use of the charge and discharge steps of the capacitor. Modulation is extremely important for power regulation.

It's possible you have a bad capacitor. Hence, the first time you power on, perhaps you end up charging the capacitor, but because the capacitor is going bad, it takes too long and the relay never trips. When you power it on again, the capacitor still has some charge left and continues to charge from that point/. This time, the relay actually triggers within specs and your computer is able to boot up.

Symptoms of bad capacitor - System memory hard faults when loading applications. When surfing web the computer will instantly shut its off and turn back on. One good one I have discovered myself was that Windows will refuse to install even if you are booting it from a fool proof USB stick. If you have tried to install Windows from a known good USB stick (that you've tested on another machine to proof it works) and the OS will not install, then you have a bad capacitor FOR SURE.

I think you're both right: When good capacitors go bad - CNET News