My PC overheated ! 
I wonder why?
Most PC's have a  fan, at least one, to keep it cool.
All PC' overheat if not kept clean.

All electronics parts (chips for sure and CAP's) do not like excess heat, too much heat and all fail, some chips get super hot and fail fast, the top 3 hot parts are , CPU, GPU and GLUE logic chips.
The 2 main processors, the CPU and GPU both can add up to 200 watts heat, full tilt. (high end  Desktop PCs)  (here RUN FAST)
  • Laptop heat can be 15watts to 100w (my HP is 50+50 watts CPU +GPU full tilt (gaming) even putting this lapton on a blanket blocks vents and it overheats fast.
  • My FX4xxx Desktop is  100watts, my Z600 is (2 xeon's) is 190 + GPU watts 50 and glue logic,  all this heat exits the rear, every drop of heat.
  • My server is Uses about 300watts but can be mover if using 16 hardisks drives and 2 processors.  (up to about 800watts)
  • The top new HP Z8 work stations with 2 skylack-x processors (400watts)  , and 1000watt PSU can burn $500 watts eash, of loaded up.
If the heat is not expelled to the room (space)  that the PC resides, then that chip overheats and can do so fast, some in seconds flat !
The CPU has over temp sensors "inside it" that cause the processor to slow down then shut down all by itself. (see here how this Intel magic happens)
The top failure modes are:
  1. All vents packed in lint. Clean them.
  2. Fans packed in lint and stalled. (2 or more fans on Desktops (real ATX desktops)
  3. Fans bad  (  or just its wire cable unplugged) Or on real desktops someone turn the fans off in BIOS, (a blunder)
  4. Heat radiator in the laptop blocked in lint ( common this)
  5. TIM failures (thermal heat sink grease failures) or even the heat sink fell off, in say shipping , drop damage. (see it many a time)
  6. The room location with PC you are in is 120 F.  sorry that won't work, RTM you users manual told you not to do that.
 Some old laptops fail to stay cool unless you add and run a free application program that lets you turn the fans no full tilt, on my HP Elitebook i7 has a hot running processor (its the fastest one) and run hot when I'm on the beach.
 By the same token my i5 laptop runs cool and never overheat but it is very slow processor. (read cheapest CPU when new is slowest)

Covering Desktops (DT) and Laptop/Notebook/pads (LT)  (this is what we call a NO BRAIN'R)
The Cure is simple.
Laptops waste  up to 15-100watts power in heavy use, is the range running fast App's, this heat is all mostly inside and must escape, if not allowed to breath and escape, and vent  the hot air, parts inside over heat and fail or self shut down.
Gaming desktops PCs can use 2 times that power level and attendant more heat.
( Blowing up a $300 CPU/GPU  is not good  ?) 
Heat is the number one killer of all electronics.!  (besides lightning and floods or you  dropped it 6 feet to concrete floor)
The ugly photo's below are all neglect. 
(even 1 year of neglect can pack a fan and faster with pets)

I will do a slide show now, to show how classic filth kills any  PC DEAD!

Most of the photos here are so captain obvious.
Vacuum it out first. (then use CAN-O-AIR  or 20psi max shop air to blow out the rest)   we use a line with a HVLP paint spray regulator to limit the force of the air pressure to safe levels. (100psi or more will damage parts inside)

Now examples show and tell:  (5years of neglect?)  Obvious !
we say RAT NASTY , at first glance.!

More examples.
Desktops are so easy to clean , just 2 screws left cover off, and gentle vacuum it out first then go outdoors next, and the use CAN-O-AIR.
I can go to the garage, fire up the (SHOP AIR) compressor set the regulator to 20 PSI, and blow out a Desktop in 5min work.  I do so once a year. (less now with my new hardwood floors)

More Neglect:

Laptops (LT) are not easy (unless lucky)  to clean or service. but lets  do some now...
The laptop can be cured in many cases(no pun) not dis-assembling the complex case , by simply blowing out ALL vents clear of lint, and for sure the 1 exit vent , be sure to back blast it., with CAN-O-AIR.
In more extreme cases of overheating one must take the Laptop apart, no 2 laptops are the same (fun no?) you must read the service manual to dismantle any laptop,  HP and DELL have those manuals, many poor Asian named, PC none exist.
Buy HP  or DELL and win, do not buy the cheapest PC, if wise.
Some PCs the keyboard on laptops come of easy,  my HP has painted logo's markes on the bottom in the shape of  a keyboard, I unscrew those and then the keyboard is free, if  then yank the cables (ribbon) the connector on the mobo is broken.
A $300 big time error, do not work on any PC LT until you learn to work the 3 classes of ribbon connectors first or you will go broke fast. (sorry)"push on, hinge clamps and wedge clamps" are the 3 types, learn those skills first !

Example Toshiba , not too old. 2008? then a 2009 HP later...
See this heat radiator, left end? "A" ARROW  below it must not be allowed to packup in lint.   (Back blast the port B now)
If the fan is dead, clean it first. This will cure most fans from stalls. (for sure hair balls from pets , ouch)
See the FAN,at "B" ?  that fan must NOT be allowed to be packed in lint , in fact if you ignore the packup this will stall the fan and the CPU will shut it all down ! overheated,  "intel inside" did that, like magic"

Removing just my keyboard or case top, helps greatly here to clean the fan and Radiator (RAD) seen here, (a Toshiba and is horrible to undo hidden plastic snaps, I hate Toshiba LT  , these was frebee, I'd never own one...ever.)
 I'm upgrading this one to LED screen for a friend. (the CCFL lamps died)
Laptops love to overheat way before any desktop. (due to that RADIATOR port being so small , see marked A above.)
The same goes for all bottom vents below, if you run the PC on a blanket it will overheat, or if the vents on the bottom are all packed full of lint, it will overheat. 
See those 6 vents on my Great Quality HP laptop? below?, do not block them or allow them to pack in lint.
SOME LT, the keyboard has vents around its rim, that suck air.  (if blocked?, oops a daisy)
ALL computers make heat,  (just like your cars engine does) and you must allow it to keep itself cool (called thermal managment to an engineer) if not?, they all overeheat.

The Below is my Elitebook HP 8540W. See the vents,  keep them clean?

The HP 8540p/w series below the key board comes off with 4 screws , the screws on mine have cute white icons labels , for keyboard.
Every year, I  back blast the fan seen here to keep the radiator clear and clean.  (I blast it both ways at all  vents and on left then at fan port)  20PSI max if using shop air like me.
Back blasting works best with keyboard removed.  (let the dust cloud float down the drive way to the street)

Facts: The heat sink tops, Not the RAD or copper pipes run at 100F (38C)   (if say the hidden radiator on the left , is packed in lint then the heat sinks get way hotter and faster, and then the CPU shuts itself down.
Most if not ALL PCs have 2  shut  down BRAINS, All CPU's will self shut down, and in almost all cases the BIOS BRIAN can too.  (goes slower then if unmanageable still, boom shuts down by DESIGN)
The GPU runs at 105f (41C)   if the fan fails or packs in lint or the RAD it will overheat real fast. (8540p) (IR thermal GUN READINGS BY ME)
The CPU shuts down at  about 90C, never let any CPU run anywhere near that. (the P4 and newer processors all HALT at 90C temp, you can not stop that, only fix the overheating cause)
A goal for any CPU is about  50C max, some go to 55C, well away from 90c trip point , see?  If the fan works below and the RAD is not packed in lint, it will run cool or the TIM is bad.
One odd  thing is if you remove all RAM the BIOS goes dead, and the fan too goes dead, so do not run it RAM free, for  more than SECONDS. My LT has 4 RAM stricks. 2 top , 2 bottom.
Test RAM 1 stick at time. (testing for bad RAM)
THE RAD can only be seen looking in the left side vent, it can be back blasted with air to clean it out, but the keyboard is best removed for the filth to land somewhere good like the back lawn or driveway, not inside case or home.

If you don't keep it clean like above, (annual)  you then  get to do this  horror.  taking the full top off, then remove 9 heat sink screws , clean it all on a bench the use this TIM  to put back all heatsinks or heat pipes
In most cases I never need to strip it down this much,  I use the air blower to blast it out 100% free of all lint outdoors.  Keyboard out , really helps greatly,  do not force those tiny connectors, learn now to deal  with them gently.
See this fan port, blasting CAN-O-AIR to the left side , can clean the RAD easy. Try that first, before over more extreme disassembly.
Some heat sinks , I discovered the HS compound turned to hard fractured glue, the cure is this.
WARNINGS: (to non-tech's)

The laptop has tiny frail ribbon connectors there are 3 types, force on,  hinge type or wedge type.  (each type is a skill set all TECHS learn fast, or go broke)
If you break one connector (not cable) , it's a $100 to $300 fix. (you get to buy a new Motherboard now)
If just  one cable is bad , you can buy them best place is Fleabay used.  Most PCs new parts sales end like in 3 years,(yes, sucks)
If you fear damage, why not ask your PC shop to clean it for you.  They know all about this  , I promise.
Best is not own a laptop at all , unless it's a throwaway Chromebook.
A Desktop is 10x more easy to clean, repair,diagnose and upgrade than any Laptop ever made.  A fact.  Do not buy $1000 laptops,  buy $100 Chrome books.
If you game, get  play station or a real Desktop gaming system.( or build on using  a Z600 ) end rant on LT.

The cure for LINT: 
Can o Air. duster

Take it outdoors, and blow it clean  using shop air or CAN-O-AIR (duster) sold in all good stores.  (never exceed 20 PSI pressure)
(I do use a vacuum cleaner first,  on the worst cases, see far above , then SHOP AIR with the 20 PSI regulator inline...) NEVER BLAST using 150+PSI shop air, ever.
Then blow all heat sinks and fans clean.  (and annual event here) always do this outdoors, never inside...
 It will be a nasty cloud like PigPen(tm) cartoon character. (wear PPE,  gear while doing this, or risk eye damage) wear GOGGLES !
You want all filth to land OUTDOORS.

Intel proof of Processor CHIP DIE LEVEL protection: "Thermal Shut Down" ( it will slow down then HALT)
CPU: (the first time you will discover this is the first time the heat sink falls off.)
The Intel chips have this feature for many many generations, it's not a new features  at all.  (THE AMD processor does the same thing for the same reasons)
I believe Pentium 4s and newer all have this, for sure most PC still running well today do this, all do, mostly.
In FACT Intel CPU (and AMD) auto self shut down and HALT when too hot. (in seconds) Read page 36
From"Intel 64 and IA-32 Architectures Software Developers Manual Volume 3 (3A & 3B): System Programming Guide" at

Section 14.5.1 Catastrophic Shutdown Detector
P4 family processors introduced a thermal sensor that acts as a catastrophic shutdown detector.

This catastrophic shutdown detector was also implemented in   Pentium 4 ™, Intel Xeon™ and Pentium M™  processors. (relics of the past now but all processors have  today)

It is always enabled !

When processor core temperature reaches a factory preset level, (90-100c?) the sensor trips and processor execution is halted until after the next reset cycle.

This  mechanism is built-in to the processor. (self contained, there)

But do know most BIOS BRAINS (code) have there own thermal controls and its own sensors and will speed up the fans or shut down the PC.  (independent of Intel magic above)

My old I-7 processor runs very hot so I run a windows app that over-rides all fans, in fact when outdoors at the beach, (hot) I run the fans full tilt (max RPM) just to keep it cool.

There are pages like this, for every Intel CPU made, this one goes in to great depth, no more guessing.

Covered here too, on modern Intel,  CORE2™. (see all pages  on thermal protections)

Question of the day 1:
Why would Intel let you burn up any $300 t0 $500 processor? answer: they do all that is possible to protect  itself from permanent damage by you, or by bad luck.
Nor will let there CPU burn up. (By Design !)

All causes listed here:
(I will not cover missing parts, or sabotage of parts inside any PC) (example: a used PC and last guy left the heatlinks all loose and installed wrong! Dang!)

  1. A Filthy PC, as stated above. See the slide show above for more horror's.
  2. The vents are simply blocked in lint or other  materials, like any laptop sitting on a blanket.
  3. The CPU heat sink (HS) fell off the CPU, touch it gently feel it, is it loose, oops. (fix this now) Mostly this happens on desktops, even shipping damaged.
  4. The The PSU or the CPU fan is dead or all packed in lint. My Z600 work station has 7 fans inside, not counting PSU, and all spin slow and quiet , until I do wild things, like run GAME.
  5. The Desktop GPU fan is dead., or case fans are dead. (a.k.a. the graphics card with a fan, all faster cards use a fan. Mostly for Gaming or CAD work. video editing /rendering, etc )
  6. The TIM failed,   (TIM = thermal interface material) or Heat Sink Grease (or compounds) , see my short page here.  We use only SHIN ETSU grease.  
  7.  The laptop  Radiator is packed , see it here. This is where all heat goes to this cooper radiator, and air must blow out the fan then pass through the RAD and exit the PC or it will overheat.
The heat Radiator device.
Are not photos great?, clear as bloody day what is wrong here,  NEGLECT, not servicing any PC of any kind , invites this problem.
That copper pipe has  Freon coolant inside, works like the refrigerator seen in mobile homes (kinda)
 The Coolant flows by convection current principles. Takes the heat off the top of the processors and lands on that RAD.
The problem in this case is it is so bad, blasting out out fails due to being packup way too bad.

end of filth.
I refuse to cover water cooled PCs, nor fanless PC's. (all are very high end $$ and complex thermal designs)
nor fake Desktops like this thing! (so called "All-In-One" PC's)

Jargon: 101
CPU, the central processor unit chip, see here.
GPU, graphics processor chip,see above link. (my GTX Nvidia cards all have fans)
MOBO the mother board seen here,  or seen here.
TIM , heat sink grease.(thermal Interfact material)
Heat sink (HS), this is  huge finned block of aluminum in  Desktop, (mine has 4) and the fins radiate heat, the purpose of the HS, is to move the heat from the CHIP to the AIR stream.
RAD is Radiator this is only seen on laptops,with a fan and thermal heat pipes,  These pipe flow heat to the RAD and then the fan blows it out of the confines of the Case to the world. (heats your room it does) even as much as 100watts heat.
PSU, power supply unit.(it too has a fan and must not be DEAD)

The HP service manual for your PC covers , dismantlement.  RTM , read the manual and not guess. hit home above, then click HP help links.
Glue logic are the other large chips not CPU, not GPU , one is called the North bridge and the other South bridges, they too must not overheat, my x38 chip runs hot and it too has  heat sink. (that must have cool air available)
If seen Glue Logic chips that have have  just a heatsink on them and seen them fall off too. ( some are clamped on others glued on (thermal glue) the former can fail easy.

version 10.  7-25-2017  (covering topic, "taking out the TRASH"), by: DeadPool  ,revised  7-1-2018