Here is my attempt to fit a magicool 240 (270 mm long):
This one is already cramped and there is not enough vent at the bottom for good airflow. That plus the slim fans and the result will be bad! An alphacool ST30 is 278mm long and I don't think it will even fit with the front IO.
What I see in your link: i7 4770 max OC + 290x max OC = 405 watts to the plug, so with 90~% efficiency, something like 360 watts on the DC, the st45sf-g is rated 450w DC.
Personaly I want to see all the mods possible in the M1, and dual PSU is one of them, but with a dual gpu card. The 290x is...
I have an i5 3350, 660ti and the fan does not even start when i play GRID2. I use an 2xmolex to 6pin pci-e adapter. You will probably be fine depending on the rest of your build. Mine has one SSD, 3 fans, and the pump from the AIO WC.
Ps: I also have one fan facing the back of the psu, idk if it...