The PC I have built my self, but there is something wrong

Hello everyone

So I built a PC on me own. The parts that I picked are (this is the website where I bought my parts from):

Case: Corsair 750D

http://www.scan.co.uk/products/corsair-obsidian-750d-black-full-tower-case-aluminium-steel-with-side-window-3x140mm-fans-usb-30-e-a

Mobo: Asus sabertooth 

http://www.scan.co.uk/products/asus-sabertooth-amd-990fx-sam3plus-ddr3-pcie-20-(x16)-quad-sli-quad-crossfirex-atx

GPU: AMD Radeon R9 280x

http://www.scan.co.uk/products/3gb-xfx-radeon-r9-280x-dd-black-edition-28nm-6200mhz-gddr5-gpu-1080mhz-2048-streams-dvi-hdmi-mdport

RAM: Corsair Vengence 

http://www.scan.co.uk/products/8gb-(2x4gb)-corsair-ddr3-vengeance-pro-series-silver-pc3-14900-(1866)-non-ecc-unbuffered-cas-9-10-9-

CPU: AMD FX 8350

http://www.scan.co.uk/products/amd-fx-8350-black-edition-vishera-8-core-s-am3plus-40ghz-16mb-total-cache-125w-retail

CPU Cooler: Corsair H100

http://www.scan.co.uk/products/corsair-hydro-series-h100-refurbished-extreme-performance-liquid-cpu-cooler-240mm-radiator-plus-2-fa

Power Supply: Corsair RM850

http://www.scan.co.uk/products/850w-corsair-rm-series-rm-series-full-modular-80-plus-gold-1x135mm-fan-atx-v24-psu

Basically my question is, what could be the reason that I can't overclock my CPU? Cuz if I do so it's getting to hot.

Since this is my first computer that I built myself I would appreciate any comments on the build and what could I have changed for better.

Thanks for everyone who reads it through. 

you said it yourself, it's getting too hot. 
how did you mount the corsair H100? did you take off the thermal paste? 

Did u apply thermal compound there? Try reseat the CPU 

Either try:

1. Applying thermal paste. (of course, if you haven't already done so)

2. If you have applied thermal paste, make sure its done correctly.

3. If all the above has been done correctly, but temps are still too high, then you will need to lower the clock & voltage of your cpu.

If the cooler cannot handle the cpu's temperature then it starts to become a bottleneck. If you want more horse power out of the cpu, then you will need to grab yourself a better cooler.

Try using better thermal paste like arctic silver 5 or prolimatech PK-3 and re-seating the H100. I have a similar set up on one of my AMD builds and had tons of issues getting the cold plate to stay put. The mounting system for AM3+ is just harder to deal with; as the cold plate of the CPU cooler tends to move around you really need 3 hands to install the cooler properly. My advice get someone else to hold the cold plate down while you put in the clips and screw it down.

As long as you keep the temps under 60c-65c (prime95) you are doing well. My 8350 is able to overclock to a healthy 4.8 Ghz stable 24/7 overclock with a H100i at 1.465 volts. (only ever so slightly better then your cooler) Also keep in mind that not all processors overclock well, AMD has more consistency then Intel, but, sometimes you do lose the silicon lottery.  

the cooler didn't had paste on it so i had to apply it.

thanks for the reply i will try it and post the results.

This usually means:

- Bad application: too little or too much thermal paste was applied, or perhaps was spread.  Use the peamethod

Also make sure the pump is running at full speed and fans are working.