Help identifying bottleneck, poor performance

[Bill2002]

I just built this system:
Athlon II x4 860k, stock cooling stock clocks
XFX r7 360 video card
8gb ballistx sport ram
400w nameless power supply

And the problem I'm having is the PC has been acting up in games, such as Minecraft, and TF2.
TF2 I run at max settings, 1080p (Which my monitor is), and I pull around 60-250fps when I'm looking at something close to me, but when there are other players it drops to 80-45-ish, only going to 45 when things really got crazy on screen. This is really depressing as my old 9800gt rig gave similar performance at slightly lower settings. I'm guessing there is a bottleneck of some sorts. Now here's the interesting part, my GPU never boosts to FULL usage, usually around 800-980 MHz, however the usage in Afterburner goes UP and DOWN frequently, and sometime sits lower at like 50-70.
In games like Minecraft, it gets around 60-100 ish (Me and a couple friends play the 1.0.0 update) at 'Far' render distance.
The problem is that anything close to 60 and under the '80s fps range feels a little unresponsive and laggy.
I am fairly savy, so feel free to ask questions
Please, any help is appreciated, thanks!

 

[Rogue Leader]

"400w nameless power supply"

Power your GPU poorly and poor performance you will have.

 

[George Phillips]

That no name PSU is risky for the rest of your components that are not extremely fast but well balanced. When the PSU is running out of the juice and deciding to quit, it might take away all your parts with it. I really recommend to:
1. Replace the PSU to something with a brand. A Corsair or Seasonic PSU is not expensive but will provide much more reliable power to all your components and make them run more stably.
2. Check and clean the graphics card if there is some or a lot of lint/dust buildup.

 

[Rogue Leader]

That no name PSU is risky for the rest of your components that are not extremely fast but well balanced. When the PSU is running out of the juice and deciding to quit, it might take away all your parts with it. I really recommend to:
1. Replace the PSU to something with a brand. A Corsair or Seasonic PSU is not expensive but will provide much more reliable power to all your components and make them run more stably.
2. Check and clean the graphics card if there is some or a lot of lint/dust buildup.

The only thing I disagree with here is Corsair, their low end units (CX and VS) have a lot of problems.

Seasonic is the way to go.

 

[TerryLaze]

Both minecraft as well as TF2 need very little GPU power (that's why old GPU gave the same results) but a lot of CPU power, and single core one at that,o/c your CPU as much as possible.

 

[Bill2002]

That no name PSU is risky for the rest of your components that are not extremely fast but well balanced. When the PSU is running out of the juice and deciding to quit, it might take away all your parts with it. I really recommend to:
1. Replace the PSU to something with a brand. A Corsair or Seasonic PSU is not expensive but will provide much more reliable power to all your components and make them run more stably.
2. Check and clean the graphics card if there is some or a lot of lint/dust buildup.

Ok, so I replaced the power supply which ended up being an Antec, with an EVGA 430w psu instead of that, and I am not observing much or any difference. It's not dust, the card is brand new. I am using a drive with Windows 10 already installed on it that a friend gave me, I believe an Intel system, and amazingly it booted with no issues. I uninstalled ALL old drivers and put on the new ones. I'm beginning to think that maybe windows is having CPU issues because the old install was with an Intel CPU.
Games like Rust and CS:GO also run as expected, however CS:GO never drops below 60, although it does hover around there during intense situations.

 

[Rogue Leader]

So replacing an Antec wasn't the best choice there. I wish we knew what it was before you replaced it. Because you said "nameless" we assume that it must be bad (since generally they all are).

Now as for using a copy of Windows 10 that was installed on another PC, generally a bad idea. Even with new drivers installed that is KNOWN to cause performance issues. Re-installing Win 10 properly may well cure your issues.