Mac mini dying?

[Ereptor]

I have been a PC guy all my life and used to think i was fairly proficient with tech and IT. However about 4 years ago after having two kids i bought a mac to help simplify things. So here is my problem. I can't watch youtube ( it is very slow and jumpy ) I can't have more than 2 programs open at once ( slow, freezes, or takes me to the login screen ) and even if i have only one program open it is still slow. Okay so specifics:

Mac mini (Mid 2011) (OS Yosemite 10.10.2)
200 GB free of the 500 GB hard drive
383GB free of 3TB External Harddrive
16 GM of 1333 DDR3 Ram
3 monitors

Okay my questions.

I have had 3 monitor set up for at least 3 years and haven't had a problem but i am wondering if that is part of the problem. but when i turn two of them off it doesn't get much better.

I have my itunes and iphoto and stored on my external harddrive. I am not sure if that is causing some of the slowness.

My CPU load playing youtube and typing this is about 40-60% with 40-50% idle.

Also I have most of my documents on drop box. I am trying to free up everything i can on my internal drive and keep everything else on the external on the cloud.

What am i doing wrong? Is it dying and on its last breath? Is there anything diagnostically i can do? Help!

Thanks for looking .

 

[Fishrrman]

What version of the OS are you using?

 

[Ereptor]

Yosemite 10.10.2

 

[gpspad]

You think of trying to run a standard benchmark test and compare it to a similar model?

 

[Ereptor]

How would i do that?

 

[Micky Do]

Run the Apple Hardware Test

This would seem to be a good place to start:

https://support.apple.com/en-za/HT201257


First two steps:

1 - Shut down your computer. Then, press the power button to turn it back on.

2 - Press and hold the D key before the gray startup screen appears.

3 - …………..

 

[Fishrrman]

With Yosemite, you really need an SSD to deliver [at least what I would consider] an acceptable level of performance...