Computer making rattling sound. Slow to start up

its been making the rattling sound then what sounds like a fan speeding up at ( like a screw is loose but when i look inside i dont see anything shaking abnormally) startup for a few months now but it usually stops after about 3 minutes
2 days ago the revving turning into a different type of revving sound like a start and stop sound
now the monitor light turns yellow for about 15-20 seconds before it gets to windows
do u know what it could be or how i could fix it thanks in advance

 

You need to do a visual inspection again and make sure the blades are not scraping a wire or something similar. If you see nothing, this is most likely a fan motor failing - typically due to worn bearings. There is no way to permanently fix this but to replace the fan.

However, because the cavernous space inside a case can cause noise and vibrations to reverberate through the case, it is often difficult to pinpoint exactly which fan is causing the noise. But this is not hard to figure out.

Open the side panel of the case and touch bare metal of the case interior to discharge any static build-up in your body. Then, with a steady hand, very carefully and gently touch the center hub of the suspect fan for just a second. This will cause the rotation speed to decrease momentarily. If that is the bad fan, the pitch of the noise will change as the fan speed changes. If you don't hear any change, move to another fan until you find the offending one.

For hard to reach fans, you can use a wooden glue/Popsicle stick. Note that hard disk drives also have motors and they will - eventually - wear out too. You can often detect which drive by gently placing your finger on the drive's case (not the circuit board) and feel for excessive vibrations.

Having said all that, a failing fan normally would not having anything to do with monitor unless the fan speed is so affected it cannot cool the CPU properly.

 

How about HDD going south?

 

just bought the computer a year ago
could it be going bad already ?

 

Seen hard drives go South within weeks and seen some that were 15 years old and still humming right along.

 

I've had hard drives with excessive vibrations and noise (due to bad bearings) right out of the box. Until Man can create perfection 100% of the time, there will always be premature failures. As I said in my last post, if you cannot find an offending fan, rest your hand on the drive and feel for the noise. If you have more than one drive, pull the power from the secondary (not boot) drives.

 

You can use a plastic handled screwdriver as a listening tool. Very carefully touch the screwdriver blade tip on the HDD case (make sure you don't short the screwdriver against live connectors) and place your ear to the screwdriver handle.
I used this method in the motor industry to listen to alternator bearings and Tappet noises. You will need a long screwdriver (usually about 12 inches long with a shaft about ¼" dia.) and lightly hold the handle between your fingers.

 

before i took your guys advice my hard drive was 75%% full, deleted alot of excess files i didnt need took it down to about 40% used space
when i tried to restart to do the inspection the noise went down significantly to where i could barely hear it
could this be a sign the hard drive is ready to go ?

 

The amount of free space on the drive would have nothing to do with noise, unless the drive was heavily fragmented. But still the resulting noise even then would not be as you described (like a rattling, loose screw).

There's really no reliable way to predict when or even if a drive is "ready to go". All you can do is (as always) keep current backups.

I also recommend you run CCleaner or Windows' own Disk Cleanup on the drive to remove any clutter. I don't see what version of Windows you are running. If a newer version, defragging is automatic (unless you dinked with the default settings). Still, you can manually defrag the drive.

Then, from an elevated command prompt (run as administrator) run chkdsk /r or run "Error checking" from the drive's properties menu. Either method will probably ask you to run the checking at next boot. Follow the prompts to allow that to happen, then reboot. Checking could take many hours and even appear to be frozen or locked up. Just let it run. It will eventually finish.

 

My 1st HDD failure noise the odd ticking - the 2nd. was a very distinct clackety-clack. So be prepared for anything from quiet to noises of any description.
You may be lucky - but 'to be sure' I would be getting an SSD ready.