I got PC noises that are Abnormal.           

How to find the source of any noise, and why it fails and how to cure it.
First off, the only cure for grossly intermittent noises (rare) is patience, and keep the left side panel open , to catch it.
Never hot swap( hot plug) any cables inside any PC, okay?

I hear odd NOISES,  that is  an Abnormal noise?  "rattles, chirps, screams ,squealing , beeps, buzzing, rattles you get the idea.."  (or Marty is inside?)
Desktops only here  as laptops , most folks are afraid to dismantle it, for good reasons, (causing more damage than cured)
Clean the beast first, even if 1 year old.?, this is the  prime reason for noise is this, due to  2 reasons filthy, find the dust bunnies.
1: The lint packs fan blades and they make a racket.
2: The PC overhearts   AS SEEN HERE.). or .(fans all running super fast or screaming load is your noise?)
The other top causes of noise are bearings, all fans have 2 bearings inside that will fail. (same with HDD and DVD drives) (endless types of noise possible)

have 5 to 10 year life span, less if on 24/7  and vast failure modes, seen HERE.

The sound has only 5 sources:  (macro thinking, big picture)

  • Old fans can make abnormal noises in all PC's, because the.Bearings and all these reasons in this list.
  • The PCs sonic beeper (BIOS POST error noise make) is beeping or LED BLINK CODE or even 4 LED binary errors seen on many DELL PCs.
  • WINDOWS, SOUNDS TURNED OFF DO NOT MUTE BIOS BEEPS. (Best is to remove the BIOS beeper ,or if soldered down put tape over its sound port)
  • Some loose metal or plastic, in the PC is vibrating and making noise in sympathetic vibration of say a bad fan OUT OF BALANCE)
  • Anything with a motor inside, fans, HDD, DVD/CD/BR-D drives can make noise, failing or about to fail worse.
Testing with tools and ears and hands:
If you get to  thinking Windows makes noise,  turn off the sound USING THIS.
Or don't let the PC boot, let it set inside any BIOS screen (mine is F1 or F10 on HP) and if it makes noise in BIOS,  Windows, OS has nothing to do with your noise.
The Next step testing is I use a card board tube, from an expended roll of  kitchen paper towel ROLL.(for my EAR)
Open the left side of your PCs cases (desktop) with latch or 2 screws rear, (per your service manual )The cover is off and you  can no find noise source.

Put one end of the Roll to your ear and listen very near at 1-inch from all fans  PSU rear,, CPU , and  if present GPU fan or at the case fans common on gaming or very fast machines.
If you find a bad fan, try tightening its mounts or screws or if that fails replace it, easy no, you found it so fix or replace it.
The fan mounts some are just cheap frail plastic, so  if it cracks the mount is bad. (again replace it, obvious but from now on all things found bad, replace it)
CPU heatsink  fan mounts bad,  common, or the new intel fans with the 4 plastic snaps; I abhor, snaps. (failed)
If you look and see the motherboards sonic beeper device, use the same ROLL tube to prove it is the culprit,if yes, then read you service manual and learn what the BEEP errors mean. 
The BIOS runs this sonic beeper not windows , windows runs audio sounds to real speakers. (and sure those sound can be horrible, for sure with bad drivers)
The beeper is seen here, clear as day. (old PCs had a dinky 1 inch speaker, for 20+ years)
The other beeper seen with 2 wires, and 2 pin clip fits a motherboard jack and is marked speaker, but is not Audio, its only for BIOS beeping and can be simply unplugged, to prove it is not beeping.

On modern PCs (above is 10 years old 2009)  The modern  (approx. 2010+)PC has no beeper now, considered now a nuisance.
There are more tests to do if the above fails..
Run the PC with the HDD unplugged  (if 2 or more HDD then pull  them 1 by 1, to find the one that is making noise) ( just the power cable pulled (red/yellow wires)

HDD can make noises (it has motor) just before they die or go dead,  most times we call this a crashed HDD.
HDD can do a very load repeating click sounds (bad HDD) not the normal very weak, light ticking sound with ear to case, if you stand say 2 feet away the drive most not click load and fast and endless.
Hard disk drive checks?. (just unplug it , noise gone?, HDD normal sounds, starting
Unplug the CD / DVD or BluRay drive next,  as those too can  make noise when bad or cracked disks inside.
Make sure the CPU fan is not loose.
Make sure the CPU heat sink is not loose on the CPU,  or OMG fell off. (oh my golly) (or eject the tray and see if the DVD drive is now quiet?)
GPU fan, CASE fans bad?
Make sure all screws in the PC are tight. (never loose and rattling about)
Some nice PCs have plastic cooling air baffles in the PC directing cool air over parts,  sure not loose works. (top quality PC have these)
Cables not hitting fan blades  or other things?
One more , could remove the PSU and bench test it for noise.!(and its noisy FAN)

I think I got them all here.?  Bad fans and HDD top my list,  but any thing can get loose and make noise, unless PC is silent type new, no fans and 1 SSD , that are all silent.(thin tablets?)

One can use more fancy tools if you have $5  to spend.
I use a dirt cheap $10 stethoscope sold at all auto parts stores on earth, to listen for bad fan bearings., or to see which fan is in trouble.? (bad fans always give and early warning before they fail hard, they make noise)

Poor mans stethoscope.:
Or put a long screw driver to your ear , handle at  ear, and blade tip to FUT (fan under test) casings.  Got noise?, it's bad. end story. (yeah replace it) 
Fans can stall, chatter, scream, buzz, rattle and chirp, bad is bad. no need fool around , replace it now. (after getting it clean and it still makes a racket it is a bad fan or some cheep knock off  junk)

Fans failure modes all ( gee if it makes bad noises, clean first of the silly dust bunny's  AS SEEN HERE.)  This should be obvious ?
  • Bearing shot after 10 years heavy uses.  (sorry chips last 100 year, fans 10, or less ,far less with cheap $1 plastic only bushing bearings.
  • Fan seized
  • Fan rattles.
  • Fan wobbles. (even tickling it (no power) with a Q-Tip™
  • Fan blade missing
  • Fan blade cracked
  • Housing cracked or loose on the mount.
  • Fan blade kissing inside of housing. (See bearing shot)
  • and last the cables are in the way hitting fan blades (desktops very common) we use tie-warps to hold them back.
  • Look first or  have persons with skills on PCs look, hear and touch.
Buy a dual ball bearing fan, steel or sst not plastic ball bearings(a cute joke from only China) 
Do not spin the fan to 10,000 RPM with  an air hose, or Can-O-air.
Buy fans that are bigger, for Case, (if case as options for that as some do)
Buy fans that have thermal sensors (case fans) if the PC has none, so only makes noise if it MUST with new sensor fans

If your Modern PC supports 4 wire fans use only 4 wire fans so the POOR PC can throttle back the RPM and run quiet.

My Jargon page is here.  Like HDD, and SSD, etc.

version 2.  12-9-2017 (desktop PCs only, most laptops making noises (bad) fans, HDD, or DVD drive bad.)