FPS Drop in every game

Do a complete preventive maintenance on your computer. This means:
-Search for viruses using a good anti virus software (Malwarebytes, Kaspersky, Windows Defender, etc.)
-Wipe out your temporary files and search for registry errors.
Simply download CCleaner and search for a youtube video on how to use it (don't worry it's as simple as turning your computer on).
-Clean your computer.
If you're afraid to do it, pay for someone to do it for you. If don't have money and are afraid you can skip this part, but remember that if you're having high temps it might slow down your games (might, it's really rare). The biggest deal on doing it is that your PC will have a longer lifetime.
-Defrag your Hard Drive (don't do it if you're using an SSD, it's a waste of time and will only reduce your SSD's lifetime)
Don't use Windows' default defragmenter it's slower and less useful than other programs. Good defragmenter options are Smart Defrag and Defraggler. I highly recommend you to use Defraggler, it's slower, but it'll also give you the best results.

Also you could try re-downloading and re-installing. Don't simply click the installer and repair the installation. Uninstall the driver, reboot, use CCleaner to remove all the registry errors you'll probably get, reboot again, install your graphics card driver and reboot for the last time. It may sound boring and a waste of time, but if you're having a driver issue (and by your post I believe you're having a driver issue) this will likely fix it.

Defrag your hard drive, it's something you need to do from time to time and among everything I told you it's what makes the biggest difference in games, believe me. Even though I don't believe it'll solve your issue it'll help.

If you already did everything and nothing worked we better start troubleshooting this issue then. Try the following:

-Stop all applications you have and play the games without any application running in the background. You won't need a program to check your fps as I believe everyone can tell the difference between 20 and 180fps.
-You said you have MSI Afterburner. Check if it's not downclocking your GPU.
Just check all your profiles to see if they're all on the standard clocks and use it's On Screen display to check your GPU clocks while playing and see if they match the clock your GPU should have. This step is extremely important. You said it happened after you watched a Youtube video, right? Some time ago I saw some posts about having your GPU clocks frozen after watching a video on the internet.
-Check if your processor is not being downclocked too.
It may happen if you have any power saving or CPU overclocking software. Find a program which will push your CPU and just run it (You can use your games for it), then check your CPU clocks (Your FX-6300 will have clocks between 3.5Ghz and 4.1Ghz if it wasn't over or downclocked).
-See if other games also had a performance drop (If you have other games and if you remember their previous performance). Maybe an update or something of the sort could have caused this drop.
-Check your temperatures. If something on your computer is overheating you'll have problems with performance.
-Check if your Catalyst Control Center settings under Gaming>3D Application Settings are set to it's defaults on the System Settings and on the games you're having drops. The default settings will be "Use Application Settings" on all settings that have this options and "Off" on everything that has this option.

This is pretty much all I can do for you with the current information I have. Do all that I told you above and return the results to see if there's still more I can help you with. And remember to defrag!

I just forgot something basic I should ask:
Are your drops constant (You can never get high fps) or do they happen from time to time (You have high fps and suddenly you get low fps)?
If they happen from time to time you are likely having overheating problems.

You said you can feel your computer getting hot, but I need number for this one. I want you to do the following:
-Download a program called Kombustor and run it. It will stress you GPU and then we'll be able to see if it's an overheating problem.
Keep it running for about 15 minutes and write down your temps before starting the test and the maximum temp reached during the test. Keep monitoring the test as it runs and stop it if your GPU gets too close to 90C as it may damage your card (I would stop it if it go over 85C).
-Download a program called Prime95. Do the same as above, but don't let the temps get too close to 70C (I would keep the same 5C security margin).

Then return me the results so we can see if overheating is the problem.

Your card seems a little bit too cool. If it's winter in your country or if you're using a really powerful cooling system it's normal, but if you're in summer and using a normal or even a relatively good cooling system it may be showing that there's something wrong with your card. If your card is set to a lower voltage or if it's not receiving enough power it may cause fps drops even if it's reaching its full clock.

I suggest you clear your motherboard's CMOS to make sure that it's not changing your GPU voltage and if your GPU uses an additional 6-pin power cable, check if its properly connected. If you clear your CMOS you'll also want to disable the startup of any overclocking software you may have, just for testing purposes.

You also need to check if your CPU is not overheating.

Don't change GPU or CPU power limit or voltage unless you're an experienced overclocker. It may screw your hardware.

I recommend you to clear your CMOS because it will make sure all your hardware is running under stock configurations and it'll be one thing less to worry about.
For how to do it, I would suggest you to see a video or search for it on the internet (just goolge "how to clear CMOS" or "how to reset BIOS", I would suggest you watching a video on how to do it) because it'll be a lot better for you to understand. Your motherboard's manual also will probably have the information you need to do it (unless you have a gigabyte motherboard, which usually has a very simple manual). And remember to uninstall (or at least disable its automatic startup) any overclocking software, to make sure it won't make changes to your configurations when the computer starts.

About the overclock your friend did, only changing the power will only increase the heat on the GPU. If you want to overclock you need to increase the core and memory clocks. The power limit will only be used if after increasing your clocks, the GPU will give you an unstable performance (something that won't happen with an unchanged MSI, since it limits how much you can overclock your card), and to do that you'll need to know several things, including your GPU power consumption, how many watts your PSU has on the 12v rail, how many connectors your card uses, how much power these connectors give to your card, etc. All that to avoid a drastic problem (which also may not happen in an unchanged MSI).

If you're still struggling with FPS drops, there's one thing you could try: There might be a program running in the background which is slowing your games down. To see if such program really exists, you have to download a program called Razer Game Booster, check on how to use it (it's very simple) and use it. It'll simply stop all background applications while you're gaming and start them again once you stop, which means that if a program is slowing your machine, it'll stop this program and you'll get your performance back.

I don't know what that means, but this shows the problem may be in your motherboard.
I can only recommend you to update your motherboard's BIOS. If it's outdated, it may have problems with some other hardware in your computer, and if it's corrupted it'll cause your computer to behave weirdly. Again you should search on how to do it as it differs a little bit depending on your motherboard's brand and age.

The only thing to do now would be getting a new formatted hard drive (or formatting your own) install only the drivers, one game and fraps (to monitor your fps, I wouldn't use any other program) and see if the problem disappears. If it doesn't you'd need to get some compatible hardware and replace piece for piece until you find what's causing the problem.
But all of this can be boring and expensive. Your best option now would be bring your computer to a technician, just don't let him deceive you telling you need an upgrade or something which will make you spend money you don't need to.

Weird. One of the reasons I told you to use game booster is that it was supposed to stop these kind of processes.