Windows 7 - Dell Dimension 5000 weird noise Fan

Hello, Everyone I have a little hardware problem with my dell

So when the computer is on for (like 4 hours) and when the cpu reaches like 70 a 100% cpu usage the computer is making a weird 'Vwrrrrrrr' noise. the normal noise (when it is just on) is a quiet noise

I think it's the fan that makes that noise but I'm not 100% sure so what can it be for sure ?

Is the fan broken or should I give it a new layer of thermal paste ??

My specs are:

Pentium 4 HT 3.00Ghz (2.99Ghz). (LGA775)
Windows 7 Ultimate (x86).
Fan is the standard Intel one
Video card is a Ati Radeon X300SE 128mb Vram

If you need more specs ask me please

if you bump the computer lightly near the fan, does it stop?

after a few years you might have problems with dust clogging the cooler, dust wont make it sound different

When was the last time you opened the case and removed the dust build up? The fan is where dust builds up most. When dust builds up, the cpu runs hotter, the fan whirs more, the dust accumulates, ad infinitum.

I Cleaned the Fan a few days ago so..

I'd be inclined to check and replace the thermal paste.

Ok will do. if I put a new layer of therminal paste on it then I will post the results if it's fixed or not

Not wishing to be patronising, but you might find this article useful.

Maximum PC | How-To: Properly Apply Thermal Paste and Install a CPU

Dell fans will spin up when the CPU heats up or is very busy. I do a lot of support on the Dell users forum and this is a common complaint. New thermal paste - Arctic Silver is recommended - will help, but it's just the nature of the CPU fan. I have a Dell Dimension E510 (basically the same as your 5000) and it's very quiet unless the CPU is busy and it warms up.

Dell uses a proprietary fan, and cooling system. Dell fans also have a built in thermal sensor and if a non-Dell fan is used you will always get a "Fan Failure" notice at power on have to press F1 to continue with the boot. It would take major modifications to use a non-Dell heatsink assembly.

Well.. Can I fix that 'Fan failure' anyway ?

If the thermal paste doesn't work I would choose this fan will these one work ?: Arctic-Cooling Freezer 7 Pro - Intel 775/1156/1366 - DCACO-FP701-CSA01 - CPU Coolers - Coolers - Codima

You can't fix the fan failure with a non-Dell CPU fan as the BIOS integrates with the sensor and if it's not there it gives the "Fan Failure" notice at the power on POST (Power On Self Test).

You have two options, continue to use a Dell proprietary fan (or a non-Dell that has the Dell proprietary sensor) or use a non Dell and always get the Fan Failure notice and you will have to press F1 to continue with the boot.

As noted, in order to use a non Dell CPU cooling system will require extensive modification to the motherboard (if it's even possible). And, you will get the fan failure notice.

Your best option is to use the Arctic Silver thermal paste and go on with the old PC. Place the PC Tower so it is getting adequate air circulation. A computer desk compartment is usually not a good place if you are having heat problems.