System wont start

[Celsius22]

So I bought a new mobo and psu for my new gpu. I've watched in youtube that you can replace your mobo without fresh install of O.S so I did it. I uninstall my drivers and then put the cpu in the new mobo
* I dont have the OS CD because it in my brother and my brother is really far away*

So I put the cpu in the new mobo I connect the psu but there's 2 cable that is not plugged I believed it is for SATA cables.
BUt the System wont start
The CPU fan doesn't start,the PSU, the LED in the power button doesnt start.

So what I did was to put the mobo in my old chassis but its still the same. but in here I don't know if the wire on my old chassis is working but nevertheless it is still not booting up or even lighting.

My hypothesis are
I plugged the wrong cables or miss to plug some?
Old Chassis wires?
I broke it?

Also I put the thermal paste in the cpu
do I need to reapply it because it is not spread due to the fan is not working because.. yeah the system wont start

 

[mudpuppet]

You have the 24 pin and 4/8 (or 4+4) connected to the motherboard, correct? Replug them if needed to make sure they are seated properly. Make sure the PSU doesn't have an on/off switch that was tripped, and that the power cable from that to the wall is plugged in well. Past that, you have the case button wired to the motherboard, correct? Check that connection as well.