Problem with GTX760

Hi, i own a ASUS GTX 760 DC2 OC edition which is about 6 months old and has been fine up until the end of last year, it runs fine most of the time but now and again in game the framerate will drop to 20fps and the card seems to lock up with the temp at 50c and the fan at 50% i asked asus but it was just some guy reading off a list so wasnt very helpful, any help would be greatly appreciated.

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System Information
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Time of this report: 2/4/2015, 12:30:20
Machine name: KENDIS_MACHINE
Operating System: Windows 8.1 Pro 64-bit (6.3, Build 9600) (9600.winblue_r3.140827-1500)
Language: English (Regional Setting: English)
System Manufacturer: To be filled by O.E.M.
System Model: To be filled by O.E.M.
BIOS: BIOS Date: 04/03/14 16:35:37 Ver: 04.06.05
Processor: AMD FX(tm)-8350 Eight-Core Processor (8 CPUs), ~4.0GHz
Memory: 16384MB RAM
Available OS Memory: 16284MB RAM
Page File: 5118MB used, 13597MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.03.9600.16384 64bit Unicode

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DxDiag Notes
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Display Tab 1: No problems found.
Sound Tab 1: No problems found.
Sound Tab 2: No problems found.
Sound Tab 3: No problems found.
Input Tab: No problems found.

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DirectX Debug Levels
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Direct3D: 0/4 (retail)
DirectDraw: 0/4 (retail)
DirectInput: 0/5 (retail)
DirectMusic: 0/5 (retail)
DirectPlay: 0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow: 0/6 (retail)

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Display Devices
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Card name: NVIDIA GeForce GTX 760
Manufacturer: NVIDIA
Chip type: GeForce GTX 760
DAC type: Integrated RAMDAC
Device Type: Full Device
Device Key: Enum\PCI\VEN_10DE&DEV_1187&SUBSYS_847A1043&REV_A1
Display Memory: 4033 MB
Dedicated Memory: 1985 MB
Shared Memory: 2048 MB
Current Mode: 1920 x 1080 (32 bit) (60Hz)
Monitor Name: Generic PnP Monitor
Monitor Model: Acer S220HQL
Monitor Id: ACR02D6
Native Mode: 1920 x 1080(p) (60.000Hz)
Output Type: HDMI
Driver Name: nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
Driver File Version: 9.18.0013.4725 (English)
Driver Version: 9.18.13.4725
DDI Version: 11
Feature Levels: 11.0,10.1,10.0,9.3,9.2,9.1
Driver Model: WDDM 1.3
Graphics Preemption: DMA
Compute Preemption: DMA
Miracast: Not Supported
Hybrid Graphics GPU: Not Supported
Power P-states: Not Supported
Driver Attributes: Final Retail
Driver Date/Size: 1/10/2015 08:07:47, 17250776 bytes
WHQL Logo'd: Yes
WHQL Date Stamp:
Device Identifier: {D7B71E3E-52C7-11CF-8661-77A41CC2C435}
Vendor ID: 0x10DE
Device ID: 0x1187
SubSys ID: 0x847A1043
Revision ID: 0x00A1
Driver Strong Name: oem6.inf:0f066de34a988f8e:Section037:9.18.13.4725ci\ven_10de&dev_1187
Rank Of Driver: 00DA2001
Video Accel: ModeMPEG2_A ModeMPEG2_C ModeVC1_C ModeWMV9_C