Hp Computer Won't Boot Until Heated with a Hair Dryer...Why? And CPU Fan Acts Strange

I have an HP computer that wouldn't boot.  I was sure the motherboard is malfunctioning as installing another power supply has the same issue.  That being won't power on and a blinking PSU light.  This being said I found the below video and figured why not.  After following the instructions in the video the machine now boots.  Odd.  Curious to know why this is.  

The CPU fan was very noisy so I replaced it with an after market fan and heatsink.  The problem is the fan will move at start up then stop.  Almost as if the system isn't strong enough to start the fan.  If I move the fan with my finger to get it started the system will run fine.  If the system is rebooted all is well.  However if I shut the system down then back on the fan must be manually push started to work.

Thanks in advance.

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AnonymousConnect With a Mentor Business Consultant (Owner)Commented:
What about the FAN not starting unless I give it a nudge?

You could have a bad aftermarket fan. Some are cheaply built to entice low price purchasers.

It could also be a weak power supply (heat affects it) needing enough voltage to run the fan.

I have had serious electronic instrumentation that would take 20 minutes to warm up before working properly. So heat affects things both ways depending on the components.

.... Thinkpads_User
AnonymousBusiness Consultant (Owner)Commented:
You heat with a hair dryer to make it work. So then heat causes parts to expand (not shrink). So the likely suspects are (1) CPU / GPU not making good contact with heat sink and heat corrects this and (2) more likely a solder joint, trace, component on the motherboard makes contact or kicks in with heat.

I would carefully reinstall the fan and heat sink. Use a thin layer over the complete surface for making proper thermal contact.

If no go, the motherboard is probably bad.

.... Thinkpads_User
1namylnAuthor Commented:
I'm heating the PSU not the CPU.

The paste is applied well.  

What about the FAN not starting unless I give it a nudge?
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Check the Electrolytic Capacitors in the PSU and the mainboard. If you see and signs of them bulging, leaking or cracking, replace them. Also replace the CMOS battery. As for the fan, either replace it, or, after cleaning off all dust, oil it a little so it runs smoothly.
Boot it into Bios and hopefully it has some power management that shows current voltage.  I am thinking that the Power supply needs replacing.  Heating up the power supply increases conductivity in components.  Replacing PSU may also solve the Fan issue.
dbruntonConnect With a Mentor Commented:
There are three questionable components here:  the two power supplies, the motherboard and the fan.

And now some questions:

Does the first power supply start up if you apply the hair dryer trick?
Is the second power supply brand new?

Did the worn out fan start up normally with the second power supply?
i would troubleshoot the different parts here; you may have more than 1 bad part.
test the PSU's on a working PC
check for bad capacitors on the motherboard -  what system is this, or mobo model?  some are famous for bad caps - note that the bad caps can also be IN the PSU
here an example of bulging , leaking ones : c
a good way for troubleshooting is the minimum setup, as described in my article here :

http://www.experts-exchange.com/Hardware/Components/Motherboards/A_1945.html                  (Short-overview-of-how-to-troubleshoot-bad-hardware-when-a-pc-does-not-post)

***note that if you heat the PSU like that for 2 minutes, the inside of the PC get's hot also
Aditya AroraNetwork & Hardware Commented:

I have the same issue long back in my old desktop. later i find that my motherboard is having bad capacitors as (nobus is told) replacing bad capacitor solve my issue.

In my case i dont have to use hair dryer, i only need to wait for 5-10 min to system start booting process.
Does the PSU's work fine on other computers?

I've had a PSU be working but took X time to work from a shut down. each shut down would take longer to recover from than the last. when i had it replaced it was up til 15 minutes.
1namylnAuthor Commented:
Two bad/failing PSU's.  New fan is also bad as old fan works with no issues.  Fixed one problem anyways.  No swollen or bursted caps that I can see.  Didn't pull the PSU apart to check.  Easier to replace.
AnonymousBusiness Consultant (Owner)Commented:
@1namyln - Thanks for the update and I was happy to help.

... Thinkpads_User
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