Most likely you won't be supplying enough power to the mobo. You should be able to get a converter to go from a molex connector to 8 pin cpu.
Will this suffice or is it advised on just getting the right psu?
What board is this? The 4/8 pin power connector doesnt power the board its the CPU power connector. It really depends on what board and CPU your going to use.
Heres the board
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128395
And heres the cpu
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103724
And heres the psu
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371006
Basically gonna be an HTPC....
In the manual it says you can use just the 4 pin connector. You should be fine with that processor. Unless you start really overclocking it. The next thing you get I would suggest getting a bigger power supply.