iMac much slowers after I installed SSD Drive.Why?

As a test, though I'm thinking it has to do with the moved HDD or the cable...

Safe Boot from the HD, (holding Shift key down at startup), does the problem occur in Safe Mode?

EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac.

http://www.etresoft.com/etrecheck

Pastebin is a good place to paste the whole report...

https://pastebin.com/

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck.

EduardoT wrote:

...a 500gb hard drive that was having some issues making some noize and freezing for a while sometimes.

...I also installed my old HD in the place of the cdrom...

...What can my iMac's problem be? Any ideas?

Sounds like the old hard drive was about to fail, is that the same hard drive that you kept in the machine but moved to the CD-ROM cable? Just to clarify, you still have the same old hard drive in the machine that was causing problems, and you are asking why you are still having problems? I am not sure what you mean, just want to understand your question a little better.

The fan issue was due to a missing thermal sensor on your new hard drive, even though the SSD will run cooler, you still need the thermal sensor cable so that the computer knows how much cooler it is running. You can find that cable at OWC.

EduardoT wrote:

...I am using the old Hard Drive as a secondary hard drive.It is still working....

But, is it, really? That bad hard drive is bringing down the whole system like a well-placed proton torpedo in an exhaust vent on the Death Star. Try un-mounting it in Disc Utility, i.e. "Eject" the disc and see if your problems go away. It will remount the next boot. If you don't have a full backup, it may likely fail half-way in the process of backing it up now.

BDAqua wrote:

Open Activity Monitor & see if fsck is constantly running.

That is also a very good idea to fall on deaf ears.

He could also run /Applications/Utilities/Disc Utility.app to run First Aid on that drive (basically the same thing) and run it again until it reports no errors, as if another suggestion or diagnosis will be any help at this point, but you never know. I am going to just return my face to palm for a minute here.

EduardoT wrote:

thank you but the problem happens right when I am rebooting.It takes long time to turn on or to reboot after that it works fine.

Classic symptoms when you have a failing hard drive installed in a computer. Just because the hard drive is no longer a boot drive does not mean it won't affect the performance of the computer. That hard drive has serious issues and needs to be removed.

You must include critical information when posting, the version of Mac OS that is installed and how the SSD is connected and if it internal or external.

Open Activity Monitor & see if fsck is constantly running.

Great idea for a test! :)

:)