Whining Noise - hardrive or fan?

Is the whining noise coming from the engine compartment where the compressor is located or is the noise coming from inside the car? If the noise if coming from inside the car it could be your blower. When a blower wears down the bushing is the first thing to wear down and it begins to have play. That makes the blower/fan vibrate making a loud whining noise. Replacing the blower could solve that whining noise.
If the noise if coming from the AC compressor, it also could be a bad bearing within the compressor.

Open the hood. Listen for where the noise is coming from. Fix the thing that is making the noise.

accord to my books this tractor has a wet clutch transmission (12 speed) , first thing is to ck your fluid level in transmission , this is bit hard to reach on this one but is possible second obtain a small sample of fluid from transmission, have it tested , It can tell you alot , second you mention that hydraulic pump overloads engine with simple tasks like raise 3-point, this could be a stuck pressure relief valve due to yep you guessed it dirty filter (it bypassed itself) ck hyd fluid for proper level and clarity ohh and one more thing this tractor uses hyd pump for power steering (some others have 2nd pump for this) is it possible that noise is coming from that area , cus I have had to replace power steering valve on that model once for a loud Noise reason
remember if your gonna have a all hydro tractor save yourself a lot of grief and periodly wash shaft seals with water sure saves a lot of grief and leaks !!

check the oil level

This particular main board doesn't have the video integrated into the mobo, so it's got a video card. Often the video card has a fan. The fan could be causing the noise. Have you tried briefly unplugging the processor fan to see if the noise stops?

The pump is cooked, needs a new one

Could be your alternator or a bad idler pulley. Is the transmission good? It may be the tranny or your differential whining.

Check your transmission fluid level, as recommended in the Owner's Manual. Also, if your car is equipped with power steering, check the fluid level in the power steering reserve.

If all fluids are at recommended levels, see if you can locate the noise. If it is in the engine compartment, try to determine if the noise is coming from any of the serpentine belt pulleys.

Sometimes the bearings on air injector pumps fail in higher-mileage vehicles, first causing a "whining" noise, and ultimately resulting in the serpentine belt "chirping" or squealing on acceleration. Best you can do is make sure all fluids are at recommended levels, then try to pinpoint the source of the whining noise for further diagnosis.

Hope that's helpful!.

Whining noise is something in motion or moving.Does the graphics card have a onboard fan?Is it clean and free moving.

How about the processor fan? clean,free from wires or anything hitting it.?

Disconnect hard drive and see if you get the sound.

I had the same whining noise, but after a minute or two it would go away. It turned out to be my water pump. It wouldnt turn first thing in the morning and the belt was just running through the pulley, (causing the whining noise). This may not be your problem, but it is easy to check. Just pop your hood and see if the fan is turning.