Macbook Pro mid 2012 15" Freezing Inconsistently

Question

I've had quite an ordeal with my Macbook Pro over the last few years, so this will be a lengthy question, sorry in advance. Let me get right to it.
Backstory:
I bought my MBP 15" new in summer of 2012. I had 8GB of laptop ram that had been in my mother's older MBP so I went ahead and put that in to increase from 4GB. A week or so later I was playing a game (Borderlands) and my computer froze. Not just the game, but the entire computer froze and I was forced to do a hard restart. It worried me a little because it was brand new, but it didn't happen consistently so I didn't think too much about it. From then on the computer started completely freezing more and more consistently, and not just with games, but while I was on the internet and in other programs such as Adobe Photoshop and Premiere. and I was forced to do hard restarts often. I upgraded to Mountain Lion when it came out, and the problem persisted. The freezing got to the point where the screen would pixelate and get full of artifacts and blocks of glitchy colors while the sound started looping and popping until I did the hard restart. I took the computer into the apple store and they ran some tests and told me that the 8GB of ram I had put in was the wrong speed for my computer, but that as long as I changed it I shouldn't have any problems. I went home, changed my ram back to the original ram that came with my computer, and lo and behold, it got worse. it started to freeze on startup and I would have to try multiple times before it would start up, sometimes it would give me the three beeps, so I knew it was a memory problem. So I bought 16GB of the correct type of ram (1600mhz instead of the 1333mhz) and the problem seemed to stop for a few weeks. Then it started again, slow at first and then in waves where it would freeze multiple times in a row and then not at all for days or even weeks. So i took the ram out and cleaned it, thinking that it might be the ram slots acting up or a bad connection, that wasn't it. I took it back into the store to be tested, but they couldn't reproduce the freezing I had, which is just my luck..soon after that my warranty ran out, so I was on my own. I started to just deal with it because it started happening less often. Finally at the end of this summer I reinstalled OS X Mavericks because I read somewhere that someone was having a similar problem and that fixed it. I did a clean reinstall and it started running great. I started reinstalling the main programs I use (Adobe CS6, Steam, a few games, firefox, VLC, ZBrush) and it was still working fine. I played Borderlands 1 on it and it froze the entire computer soon after I started playing. I thought that might just be because that game is a port and I bought it through the Appstore. So I took it easy and the computer did well. Then I started playing Borderlands 2 (on the lowest settings to be safe) and the computer worked great, even though I played for 3 or 4 hours at a time. I thought all was well now. That was until I came back to school and then last night my computer started freezing again. It is not as bad as before, and I've only been able to reproduce it consistently while playing Borderlands 2, but it bothers me that my computer is not solid, even if it doesn't freeze doing most other things.
If I thought it would be fine if I stopped playing games on it, then I would stop and be fine with that, but I think the problem is bigger than that, and that is why I am asking for help.
What I've Tried So Far (in order, kind of):
1. Changed the ram to 8GB 1333mhz - computer started freezing after that
2. Took it to the Apple store to get it checked out - they told me it was the ram
3. I changed the ram back to 4GB 1600mhz - froze worse than before
4. Bought and put in 16GB 1600mhz - ran fine for a time, then started again
5. Took it back to the Apple store - Didn't reproduce the results
6. Uninstalled all games - didn't change anything
7. Reinstalled OS X Mavericks - Ran fine for a little while, now freezing during games again.
8. Ran Apple Hardware Test multiple times during all this, it would start and then freeze around 8 minutes in.
9. Booted in Internet Recovery mode - froze every time and gives me error code -3404D now, which I can't find any information about online.
10. Ran MemTest through Rember multiple times. Before reinstalling OS X it froze every time, now my ram passes every time.
11. Checked Activity Monitor, and ran EtreCheck - I'll post the results below, but everything seems normal to me.
12. Checked memory usage while playing Borderlands 2 (windowed, lowest settings still) the game was using about 1GB of ram, then my computer froze after playing for about 2 minutes.
13. Also I've taken my ram out and cleaned everything, including fans multiple times throughout this ordeal. My computer would get pretty hot at one point, and I thought it was overheating and maybe disconnecting some solder, so I used to turn it on its side and put a fan on it to cool it down and it would finally restart, but that was before reinstalling OS X and it hasn't been getting that hot recently.
EtreCheck Results as of right now:
EtreCheck version: 1.9.15 (52)
Report generated August 27, 2014 at 11:06:56 AM EDT
Hardware Information: ?
    MacBook Pro (15-inch, Mid 2012) (Verified)
    MacBook Pro - model: MacBookPro9,1
    1 2.3 GHz Intel Core i7 CPU: 4 cores
    16 GB RAM
Video Information: ?
    Intel HD Graphics 4000 - VRAM: (null)
        Color LCD 1440 x 900
    NVIDIA GeForce GT 650M - VRAM: 512 MB
System Software: ?
    OS X 10.9.4 (13E28) - Uptime: 0 days 1:14:7
Disk Information: ?
    APPLE HDD HTS547550A9E384 disk0 : (500.11 GB)
    S.M.A.R.T. Status: Verified
        EFI (disk0s1) <not mounted>: 209.7 MB
        Macintosh HD (disk0s2) / [Startup]: 499.25 GB (395.43 GB free)
        Recovery HD (disk0s3) <not mounted>: 650 MB
    HL-DT-ST DVDRW  GS31N
USB Information: ?
    Apple Inc. FaceTime HD Camera (Built-in)
    Apple Inc. BRCM20702 Hub
        Apple Inc. Bluetooth USB Host Controller
    Apple Inc. Apple Internal Keyboard / Trackpad
    Apple Computer, Inc. IR Receiver
    Microsoft Basic Optical Mouse
Thunderbolt Information: ?
    Apple Inc. thunderbolt_bus
Configuration files: ?
    /etc/hosts - Count: 6
Gatekeeper: ?
    Anywhere
Launch Daemons: ?
    [loaded]    com.adobe.fpsaud.plist Support
    [loaded]    com.adobe.SwitchBoard.plist Support
    [loaded]    com.microsoft.office.licensing.helper.plist Support
    [loaded]    com.oracle.java.Helper-Tool.plist Support
Launch Agents: ?
    [not loaded]    com.adobe.AAM.Updater-1.0.plist Support
    [loaded]    com.oracle.java.Java-Updater.plist Support
User Launch Agents: ?
    [loaded]    com.adobe.AAM.Updater-1.0.plist Support
    [loaded]    com.google.keystone.agent.plist Support
    [running]    com.spotify.webhelper.plist Support
    [loaded]    com.valvesoftware.steamclean.plist Support
User Login Items: ?
    iTunesHelper
    TuneupMyMac
    Google Drive
Internet Plug-ins: ?
    AdobeExManDetect: Version: AdobeExManDetect 1.1.0.0 - SDK 10.7 Support
    FlashPlayer-10.6: Version: 14.0.0.176 - SDK 10.6 Support
    QuickTime Plugin: Version: 7.7.3
    Flash Player: Version: 14.0.0.176 - SDK 10.6 Support
    AdobePDFViewer: Version: 10.1.1 Support
    Default Browser: Version: 537 - SDK 10.9
    SharePointBrowserPlugin: Version: 14.0.0 Support
    Silverlight: Version: 5.1.30514.0 - SDK 10.6 Support
    JavaAppletPlugin: Version: Java 7 Update 67 Check version
Audio Plug-ins: ?
    BluetoothAudioPlugIn: Version: 1.0 - SDK 10.9
    AirPlay: Version: 2.0 - SDK 10.9
    AppleAVBAudio: Version: 203.2 - SDK 10.9
    iSightAudio: Version: 7.7.3 - SDK 10.9
iTunes Plug-ins: ?
    Quartz Composer Visualizer: Version: 1.4 - SDK 10.9
3rd Party Preference Panes: ?
    Flash Player  Support
    Java  Support
    MusicManager  Support
Time Machine: ?
    Time Machine not configured!
Top Processes by CPU: ?
        22%    firefox
         4%    WindowServer
         2%    hidd
         1%    fontd
         0%    mds
Top Processes by Memory: ?
    573 MB    firefox
    115 MB    installd
    82 MB    mds_stores
    82 MB    Finder
    82 MB    WindowServer
Virtual Memory Information: ?
    11.57 GB    Free RAM
    2.21 GB    Active RAM
    1.13 GB    Inactive RAM
    1.08 GB    Wired RAM
    360 MB    Page-ins
    0 B    Page-outs
Let me end by saying thank you in advance. I take pretty great care of this computer (besides mistakenly installing the wrong ram) and physically it is in great condition. I appreciate any help.

Answer 1

Oh, and I also reset my NVRAM, my computer hasn't frozen again yet, so I'm not sure if it has made a difference.