The Fan make scrapping noises!

A fan thats making a scraping sound is likely ready to fail as the fans bearing is worn-out.

I would start there replacing it:

• Hard Drive Fan 922-8154
• Optical Fan 922-8152

If you suspect the HD temp sensor is bad you could also try replacing it:

• HD Temp Sensor 922-8165

The fact you have both sensors set to manual control (over-riding the sensors) is not a good idea! Frankly, you shouldn't need any controls (even with a SSD). What you are doing is over-riding the internal systems heat management system (SMC) which can cook your system (shortening its life) and/or wear out the fan units prematurely. I would recommend using a better app to monitor your thermal sensors (even log them) so you can see what your system is upto more effectively. I would give this one a try: Temperature Gauge Pro.

While you're inside it might be a good idea to clean & refresh the thermal paste on the CPU & GPU. as well as clean any dust build up on the heat sink fins and fan blades as well as the internals. Use can'ed air and a soft brush to scrub the dust free where needed.

The snap of your temps looks OK. You may need to stress the system a bit to see if the fan starts running rough. If you think it's the lower fan replace that one.

As to a guide to replace the thermal paste sadly there isn't one for your system. The steps are the same across all the systems. Follow the basic steps as outlined here: Technique: Applying Thermal Paste.

Here's the cleaner & paste you should use:

• Arctic Silver ArctiClean

• Arctic Silver Thermal Paste

Corrected parts list:

• CPU Fan 922-8459
• Hard Drive Fan 922-8490
• Optical Fan 922-8458

Dan, hope you don't mind me adding some images for a bit of a clarification for mamphp (see comments)