Are my pc specs good?

intel pentium G456E? Never heard of that CPU unless you mean a G4560
Then no, your CPU is not the best but it's not the best - I'd say it's good for low-medium end gaming (Not to be confused with low end; low end // low-mid (low end with medium graphics) // low-high (Low end gaming, high graphics))

CPU isn't too bad, it's pretty decent if you're looking to play on medium game's and depending on the graphics for example; GTA is more CPU Heavy then GPU (From my experience with this) where as other games such as arma 3 would destroy because it's CPU/GPU.
It's all dependent on the game.
GPU is pretty decent, it's up there and it's not that old, I believe only 2 years? (Correct me if I'm wrong) and it can handle quite a big of games graphically as long as the CPU can uphold it's end.
RAM 4GBx2? Meaning two 4GB sticks or Two 2GB sticks ... Either way, RAM is really low and in this day and age with how game's are lately I'd say 16gb minium (I would say 8GB but it all depends on the games you play too and what you run in the background)
PSU: I'd definitely get up to a 650w at minimum, just so you have the power on spare just in case, but you want something that recycles power so something like a Gold+
Mobo: It's cheap, it's doing it's purpose for you CPU as intended but I can gurantee the OC support is really trash.

I'd reccomend the CPU/RAM/PSU/Mobo to be upgraded.

Reply with a budget and a over-budget (Example; $1,000 but IF needed then $1,200) and I'll put you together a list that I'd personally reccomend. (Also sure with what you're looking to do with your PC)