Power Supply 4 pin motherboard has 8 pin socket

[mjh-p26]

working on a new build. i have Gigabyte 990x gaming sli. AMD FX 6300 black edition. my PSU is old but still works fine but it only has a 4 pin for cpu power but my motherboard has an 8 pin socket. is it safe to connect the 4 pin into the 8 pin? or should i not risk it and just buy a new PSU? my current psu is Super silent EZ cool 700w (atx-700 jsp) 12v 24 pin and 12v 4 pin

any guidance would be appreciated. thanks.

ps. i do not plan on overclocking just want it to run at stock levels.

[AgentFXA]

you can get an adapter like this:
http://www.ebay.com.au/itm/4-pin-to-8-pin-CPU-Power-Cable-Converter-Adapter-EPS-/280515548780

or plug in two 4pin cpu power plugs if you psu got two cables (do not use a molex)

the single 4 pin is an old design for weaker CPUs < 150w

other than that buy a more recent psu which gotta 8-pin plug.