Good PC running painfully slow

[Motiongod1]

Hello I bought myself a decent gaming pc and the games run slow like really slow and windows 7 is lagging aswell. Heck my older PC is working better than this one. I ussualy get around 30-40 fps in games. I've defragmented drives, reinstalled system,drivers and checked for malware.
Heres the spec:
Cpu - Intel i3-4170 CPU 3.70Gz(4CPUs) ~3.7GHZ
Gpu - Nvidia gtx 750ti
memory- 8192 MB RAM
page file - 3137MB used, 13182 availible??? don't know what is this
TOSHIBA DT01ACA100 1TB 7200 RPM 32MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive Bare Drive
Any help or suggestion would be highly appriciated as I'm on the edge of calling the store that sold me this "computer".

 

[Samaratin]

i don't think i would call that a "decent" gaming PC, i would call it a basic starting point for a year and a half ago. What games are you playing?

 

[Tumeden]

A GPU upgrade with an addition of a SSD would boost your performance quite a bit.

 

[cloudrunner14]

You guys are being unreasonable. This pc will perform games just fine - perhaps not on YOUR preferred settings but it might on his/her and we also do not even know what games they're playing. We also do not know their resolution, what if they're still on a 720p monitor?

His pc definitely shouldn't be lagging just in Windows.

@motiongod1 now you said your fps was 30-40 in games. What games are you playing and at what settings did you play them? 30-40 fps wouldn't be too bad for let's say Witcher 3 but it would be for a game like Minecraft.

 

[BadAsAl]

What is your CPU and hard drive usage from Task Manager when it is lagging?
Have you monitored temperatures (I like Open Hardware Monitor) to see if you are running hot and maybe throttling?