Dell E520 with Pentium D 820

If it is the stock heatsink, make sure to push down evenly on all four push pins at once.

Going in to the BIOS and going to PC Health etc (if available) is a simple way to see if the heatsink is on properly - its not accurate and doesn't show any kind of loaded temp, or core temp, but if the value is rediculously high (above 50) then the heatsink isn't on correctly.

You could retry using your gel, if you're not overclock the standard gel should be ok as long as it's applied correctly. AS5 can provide a couple of degrees celsius but it's no miracle cure.

I use a zalman "fan mate" series rpm adjuster, available for about $7 at frys and other venders. Check the fan port on your heatsink first. My zalman only worked with 3 pin models. I would not adjust your cpu heatsink too much, if fan noise is the only problem you have now.

If the fan is spinning up more than usual on load, then this indicates that temperatures have risen. I think that's his worry.

I don't have any advice though, you can't read the temps so it's pretty hard to make any kind of decision/advice off that. You could try HWMonitor, another free tool from the people who do CPU-Z. It'll show you fan, voltage, and temp information from any available sensor including video cards and hard discs.

No. Don't flash the bios with a dell board unless you've done it before. Dell bios will have no hardware monitor settings that other brand boards typically have, and a bios flash probably won't help. You could end up with a dead board, as the new bios program will erase the old one before flashing. I don't recommend it. If your heatsink is seated properly, I still recommend the rpm adjuster. My celeron runs at around 2200 rpm, and gets adequate cooling. I've had the rpms as low as 1500 during certain times of the year. I hate noise.

I don't understand why PCWizard doesn't work in your system. I don't think you're using the program correctly.
Download version 1.911. Run the program. On the left side side you will see what looks like a volt meter ( + - signs). Click on that and what does the information say about your CPU fan RPM?

You rCPU fan is supposed to ramp up with CPU load. Even more important you want to know what the CPU core temps are to make sure you don't have an overheating CPU!

Oops. Never mind.

I think I remember monitoring the temps on this machine a while back. Also, others with the same machine are able to monitor temps. (I actually did a google search!)
Is the sensor on the actual cpu or the mobo?