BSOD playing TF2, SYSTEM_SERVICE_EXCEPTION

Hey guys so my brothers computer has had this BSOD issue for a long time now. I recently (1.5 month ago) replaced his RAM as I believed it was faulty and this stopped the BSOD's that use to happen all the time as well as system start failures. However he just had another BSOD and it still occurs occasionally.

He mainly uses the computer to play Steam games and watch Youtube.

Things I have tried:
- Replace RAM/change Ram slot (helped a lot)
- Run memtest86 (passed multiple tests)
- Virus scans/malware scans/defrag HDD
- Full computer format (however I kept the steam folder and just repaired it)

When does BSOD happen:
- When computer is in use, I dont think it ever happens when its on standby or idle
- Usually its when a game (TF2 being the one they play most) is running

Computer Specs:
Windows 7 Ultimate x64
SSD: 256 Samsung Evo
HDD: hitachi 2TB HDD 7200rpm
CPU: i7 2600k (OC at 42Ghz)
RAM: Replaced 2 4GB sticks with 1 8GB Corsair Vengeance stick (No OC)
Fan: Cooler master hyper 212
PSU: corsair hx850
GPU: nvidia 570 SOC
MOBO: Asrock extreme 4 z68


I'm not sure when the BSOD will happen again but I have started Driver verifier and it is active right now. I don't have any steps to exactly reproduce it. Let me know if you require any more info.

BSOD Dumps:

This dumb is the most recent. Brother started TF2 from steam and alt tabbed to watch Youtube video then BSOD.

==================================================
Dump File : 020714-13322-01.dmp
Crash Time : 7/02/2014 10:27:18 PM
Bug Check String : SYSTEM_SERVICE_EXCEPTION
Bug Check Code : 0x0000003b
Parameter 1 : 00000000`c0000005
Parameter 2 : fffff800`02e445fe
Parameter 3 : fffff880`082480b0
Parameter 4 : 00000000`00000000
Caused By Driver : ntoskrnl.exe
Caused By Address : ntoskrnl.exe+6f880
File Description : NT Kernel & System
Product Name : Microsoft® Windows® Operating System
Company : Microsoft Corporation
File Version : 6.1.7600.17273 (win7_gdr.130318-1532)
Processor : x64
Crash Address : ntoskrnl.exe+6f880
Stack Address 1 :
Stack Address 2 :
Stack Address 3 :
Computer Name :
Full Path : C:\Windows\Minidump\020714-13322-01.dmp
Processors Count : 8
Major Version : 15
Minor Version : 7600
Dump File Size : 291,400
Dump File Time : 7/02/2014 10:28:20 PM
==================================================

Here is another one from January. Can't remember what was happening at time. Don't have any more dumps however.
==================================================
Dump File : 011514-10608-01.dmp
Crash Time : 15/01/2014 1:15:50 PM
Bug Check String : PAGE_FAULT_IN_NONPAGED_AREA
Bug Check Code : 0x00000050
Parameter 1 : fffff900`c2563c00
Parameter 2 : 00000000`00000000
Parameter 3 : fffff960`0034260d
Parameter 4 : 00000000`00000000
Caused By Driver : ntoskrnl.exe
Caused By Address : ntoskrnl.exe+6f880
File Description : NT Kernel & System
Product Name : Microsoft® Windows® Operating System
Company : Microsoft Corporation
File Version : 6.1.7600.17273 (win7_gdr.130318-1532)
Processor : x64
Crash Address : ntoskrnl.exe+6f880
Stack Address 1 :
Stack Address 2 :
Stack Address 3 :
Computer Name :
Full Path : C:\Windows\Minidump\011514-10608-01.dmp
Processors Count : 8
Major Version : 15
Minor Version : 7600
Dump File Size : 291,400
Dump File Time : 15/01/2014 1:16:49 PM
==================================================

Thank you very much in advance.