Stuttering lag with GTX 760?

I rececently just bought a GTX 760 and all the games I play are fine even on highest graphics (Such as Crysis 3 in 1080p and 50fps) although whenever I turn around or walk it starts to stutter

On minecraft with my old graphics card a GT 620 I would have no stutters at all and good fps, but now I get over 120fps but it stutters everytime chunks load

specs: Gpu: gtx 760 amp edition
Cpu: AMD a8 5500 apu with Radeon Graphics 3.2GHz
Ram: 8GB
Motherboard: MSI MS-7778

How would I fix this? :l

Added (1). I'll prehaps get a i5 4570, will I need a new motherboard for it? If so how much will it cost…

Added (2). 550w Power supply

Dylan

It's struggling with that weak *** system you have
The 760 is processing fasting then the a8 can feed it information

Guest

What power supply do you have? Also have you updated to the latest graphics drivers are sometimes more optimised for the latest graphics cards. The a8 isn't that bad, I can't imagine it holding back a 760. If it was two 760s then yes that would be the case. If you were to change to the intel processors you would also have to change the motherboard. The motherboard I recommend is the asus z87a which is about £110, but the ram and the rest of the components would be fine. You will also need a new windows license if you brought an OEM version or if that is a prebuilt PC.

V8VANTAGE