Mid 2011 21.5" iMac freezing constantly

Question

As of lately, my iMac has been constantly freezing. At first I had a problem with bad RAM causing kernel panics after I installed 16GB of Patriot Viper memory, I thought it was the Patriot Memory because everything was fine until I installed that. I figured it was because it was 1600 MHz and my iMac is rated for 1333 MHz. Anyways, I ran the Apple hardware test to find that the original RAM was the suspect but just to be safe, I replaced ALL RAM with Corsair RAM (8GB x 4 for a total 32GB). Now, on to my new problem at hand. My iMac is constantly freezing, everything is up to date, I have ran Disk Utility with no abnormal results, reset PRAM/VRAM, reset SMC, I also downloaded multiple third party apps to check my disks etc, and it seemed it was running hot so I downloaded iMac Fan Control and set the temperatures as follows:
Lower Temp Threshold: 46C
Upper Temp Threshold: 85C
Slowest CPU Fan Speed: 1200
Slowest HD Fan Speed: 1600
Slowest DVD Fan Speed: 1600
booted in Safe Mode and so far no freezing. Any ideas on what to do?

Answer 1

Please read this whole message carefully, especially the warnings, before doing anything.
1. I can only guess which of the modifications you've made to your system is causing the problem. The changes suggested here should be considered provisional; they may not help, or they may remove functionality that you find useful. If a third-party system modification that you want to keep is at fault, refer to its developer for support.
2. WARNING: Back up all data now if you haven’t already done so. Before proceeding, you must be sure you can restore your system to its present state, even if it becomes unbootable. If you’re not sure you can do that, STOP — DON’T CHANGE ANYTHING.
If you don't like the results of the procedure suggested below, restore from your backup.
I will not be responsible for the consequences, and I will not be able to help, if you ignore this warning.
3. You should either remove or update the following system modification(s), if an update is available from the developer:
[Not applicable]
and definitely remove at least the following:
† FreeMemory
† TechTool Pro
4. Whatever you remove must be removed completely, and (unless otherwise specified in this message) the only way to do that is to use the uninstallation tool, if any, provided by the third-party developers, or to follow their instructions. If the software has been incompletely removed, you may have to re-download or even reinstall it in order to finish the job. I can't be more specific, because I don't install such things myself. Please do your own research.
Here are some general guidelines to get you started. Suppose you want to remove something called “BrickMyMac” (a hypothetical example.) First, consult the product's Help menu, if there is one, for instructions. Finding none there, look on the developer's website, say www.brickmymac.com. (That may not be the actual name of the site; if necessary, search the web for the product name.) If you don’t find anything on the website or in your search, contact the developer. While you're waiting for a response, download BrickMyMac.dmg and open it. There may be an application in there such as “Uninstall BrickMyMac.” If not, open “BrickMyMac.pkg” and look for an Uninstall button.
Again, please don't ask me to do this research for you. You can do it better than I can, because I don't use the product and I may not even know what it is.
You will generally have to reboot after uninstalling a system modification. Until you do that, the uninstallation may have no effect, or unpredictable effects.
5. If you can’t remove software in any other way, you’ll have to erase and install OS X. Never install any third-party software unless you're sure you know how to uninstall it; otherwise you may create problems that are very hard to solve.
WARNING: Trying to remove complex system modifications by hunting for files by name often will not work and may make the problem worse. The same goes for "utilities" such as "AppCleaner" and the like that purport to remove software.
6. I recommend that you never reinstall the modifications marked with a dagger (†) above, if any. If your problem is resolved after uninstalling all the above modifications and rebooting, but you still want to use some of those not marked with a dagger, you can experiment with putting them back, one at a time, testing carefully after each step. Keep in mind that system modifications may be incompatible with each other or with future OS X updates, so it may not be clear which one is at fault.
7. If you still have problems after making the suggested changes and rebooting, post again. Remember: if you don’t like the results of this procedure, you can undo it by restoring from the last backup you made before you started.
This procedure will unlock all your user files (not system files) and reset their ownership and access-control lists to the default. If you've set special values for those attributes on any of your files, they will be reverted. In that case, either stop here, or be prepared to recreate the settings if necessary. Do so only after verifying that those settings didn't cause the problem. If none of this is meaningful to you, you don't need to worry about it.
Step 1
If you have more than one user account, and the one in question is not an administrator account, then temporarily promote it to administrator status in the Users & Groups preference pane. To do that, unlock the preference pane using the credentials of an administrator, check the box marked Allow user to administer this computer, then reboot. You can demote the problem account back to standard status when this step has been completed.
Enter the following command in the Terminal window in the same way as before (triple-click, copy, and paste):
{ sudo chflags -R nouchg,nouappnd ~ $TMPDIR.. ; sudo chown -R $UID:staff ~ $_ ; sudo chmod -R u+rwX ~ $_ ; chmod -R -N ~ $_ ; } 2>&-
This time you'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning to be careful. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.
The command may take several minutes to run, depending on how many files you have. Wait for a new line ending in a dollar sign (“$”) to appear, then quit Terminal.
Step 2 (optional)
Take this step only if you have trouble with Step 1 or if it doesn't solve the problem.
Boot into Recovery. When the OS X Utilities screen appears, select
Utilities ▹ Terminal
from the menu bar. A Terminal window will open. In that window, type this:
res
Press the tab key. The partial command you typed will automatically be completed to this:
resetpassword
Press return. A Reset Password window will open. You’re not  going to reset a password.
Select your startup volume ("Macintosh HD," unless you gave it a different name) if not already selected.
Select your username from the menu labeled Select the user account if not already selected.
Under Reset Home Directory Permissions and ACLs, click the Reset button.
Select
 ▹ Restart
from the menu bar.
Launch the Font Book application and validate all fonts. You must select the fonts in order to validate them. See the built-in help and this support article for instructions. If Font Book finds any issues, resolve them.
From the application's menu bar, select
File ▹ Restore Standard Fonts...
You'll be prompted to confirm, and then to enter your administrator login password.
Boot in safe mode to rebuild the font caches. Boot again as usual and test.
Note: If FileVault is enabled, or if a firmware password is set, or if the boot volume is a software RAID, you can’t boot in safe mode. In that case, ask for instructions.
Also note that if you deactivate or remove any built-in fonts, for instance by using a third-party font manager, the system may become unstable.