Windows 8.1 issues ever since I installed new gpu!

[Gamessilv]

I recently got a PowerColor 7850 PCS+, it was a upgrade from a graphics card (msi 6450) that already came when i bought the computer a couple weeks ago. (got it for $300, cannot beat that)

Before installing the card , i used this tool called "Display Driver Uninstaller" that people recommend using before installing a new card.
I installed the card and everything (drivers etc), but what i noticed is that 8.1 stutters alot more, when i am on chrome the pages lag to load, when i play games like mw2 , it has fps drops even when i lower the settings down (even if this gpu should run it in max) , i am not sure what is causing this. 
Temps are perfect , & it does not pass 75c on furmark but after when i am done using the benchmark , it tends to start stuttering more. What should i do ?
Also , it cannot be the ram because when i had the 6450 it wouldn't do this.

Specs , 
CPU: AMD FX-6300 Black Edition 
Non-Overclock 3.5 GHz
GPU: PowerColor 7850 PCS+
2GB GDDR5 
(Upgrade From Msi 6450 2gb)
MOBO: BIOSTAR A960D+
RAM: G.SKILL Ripjaws X Series 4GB 
(1 x 4GB) DDR3 1600
PSU: LEPA MX-F1 N350-SB 350W
(Running Dual 4 Pin Molex to 6 Pin to power Gpu)
Case: Enermax Thorex

[Senzelian]

I recently got a PowerColor 7850 PCS+, it was a upgrade from a graphics card (msi 6450) that already came when i bought the computer a couple weeks ago. (got it for $300, cannot beat that)

Before installing the card , i used this tool called "Display Driver Uninstaller" that people recommend using before installing a new card.

I installed the card and everything (drivers etc), but what i noticed is that 8.1 stutters alot more, when i am on chrome the pages lag to load, when i play games like mw2 , it has fps drops even when i lower the settings down (even if this gpu should run it in max) , i am not sure what is causing this. 

Temps are perfect , & it does not pass 75c on furmark but after when i am done using the benchmark , it tends to start stuttering more. What should i do ?

Also , it cannot be the ram because when i had the 6450 it wouldn't do this.

Specs , 

CPU: AMD FX-6300 Black Edition 

Non-Overclock 3.5 GHz

GPU: PowerColor 7850 PCS+

2GB GDDR5 

(Upgrade From Msi 6450 2gb)

MOBO: BIOSTAR A960D+

RAM: G.SKILL Ripjaws X Series 4GB 

(1 x 4GB) DDR3 1600

PSU: LEPA MX-F1 N350-SB 350W

(Running Dual 4 Pin Molex to 6 Pin to power Gpu)

Case: Enermax Thorex

Are you sure it gets enough power by the PSU?

I'm not sure if 350watts especially if the PSU is already older are enough.

But I'm probably wrong as you also have those problems at idle.

[Gamessilv]

Are you sure it gets enough power by the PSU?

I'm not sure if 350watts especially if the PSU is already older are enough.

But I'm probably wrong as you also have those problems at idle.

I will upgrade the psu soon , but first i want to fix this issue because i am positive it has to do with Windows 8.1 i just want to know exactly what. 

[Beltboy]

I will upgrade the psu soon , but first i want to fix this issue because i am positive it has to do with Windows 8.1 i just want to know exactly what. 

This issue is as @SenZilian says, your PSU isn't man enough, Powercooler tell you not to install the GPU unless you have min 500W PSU.

 

when you PSU and CPU are under load neither get enough power and run slower.

[sof006]

This issue is as @SenZilian says, your PSU isn't man enough, Powercooler tell you not to install the GPU unless you have min 500W PSU.

 

when you PSU and CPU are under load neither get enough power and run slower.

This.. This all over. AMD = Power hungry and heat output monsters. Time to get a new PSU, they're dirt cheap for a really decent one if you're in the UK you can get a 750W PSU for £70 on amazon... that in dollars is 108 dollars? You could probably find one cheaper if you searched a little on Amazon or other sites.

[0x1e]

You shouldn't cheap out on a power supply.

It's the most stupidest thing you could every do when building / upgrading a computer.

[Gamessilv]

You shouldn't cheap out on a power supply.

It's the most stupidest thing you could every do when building / upgrading a computer.

I did not cheap on it , i bought the system like this. 

 

Anyways, i downgraded to Windows 7 and there is no more stuttering. Also my new cx600m is on the way.

 

Thanks for the suggestion.