Slow performance after installing GTX 970

[xshadow]

I just bought my new GTX 970 due to my GTX 470 died and a new case because my old case can't fit in my new GPU. It works perfectly fine after my friend and I swap into the new case. When I game I got like 60-120 ish fps but when I restart my PC or long period of time and run the game again my fps are starting become decreasing to under 20-50 fps and starts lagging, stuttering and sound cutting off. The only way to solve this issue is to shut down and let it cooldown for couple minutes. I tried to clean my PC, CPU fan, re thermal paste, uninstall Nvidia driver and re install the latest with clean install enabled nothing solved.

My Specs are
CPU - Intel Core i5 650 running stock clock
MOBO - Asus Maximus III Gene
PSU - Antec Truepower 650W https://lh4.googleusercontent.com/-VoQmTJS1dXY/VMAC60bjbSI/AAAAAAAAHos/iPXYq_ViJfI/w1461-h822-no/20150121_144953.jpg
RAM - 4GB (2x2GB) 1333MHz https://lh6.googleusercontent.com/-KvOy0f9wCBw/VLtQORtofpI/AAAAAAAAHm8/wbrldNwkrv4/w1461-h822-no/20150118_011819.jpg
HDD - 3TB https://lh5.googleusercontent.com/-zkfvPayWSec/VMAgT8OPi3I/AAAAAAAAHqU/5J1GYDzaMUo/w462-h821-no/20150121_145407.jpg
ODD - https://lh5.googleusercontent.com/-QJGCOUwNemg/VMADilfmDUI/AAAAAAAAHpo/NbuRSbd04hc/w462-h821-no/20150121_145227.jpg
SSD - Samsung 1TB 840 EVO
OS - Windows 7 Ultimate 64 bit SP1

and the rest
http://ca.pcpartpicker.com/user/xshadowfear/saved/2QrWGX

 

[TheFluffyDog]

maybe your having a case flow problem? the heat from the CPU maybe is recycling over it instead of leaving the case efficiently?

Try this,
Get a CPU benchmark and a program to watch the temps, Run the benchmark and watch your temps at the same time.
Also since its happening during games, try getting a temperature monitoring program and running Unigine Heaven Benchmark while watching the temps, if you can do this we can rule out, or confrirm over heating.

 

[TheFluffyDog]

also watch the temps on the GPU, maybe the GPU you got had a Poorly set heatsink from the factory. its rare but you can either fix it at home or send it back.