Underclock GPU core frequency - possible?

[djoole]

Hi,

I've made a brand new hardware setup to use with FreeNAS, and i made a poor choice for the mobo (P8P67 R3.1)

I believed that GPU wasn't mandatory to boot the PC, well it is.

So i went and bought the cheapest/silentest/power consumption friendliest GPU on the market : a RADEON HD5450

Well, this GPU produce an unwanted amount of heat in the case, so i would like to underclock it to lower this heat.

Any idea of how to do this on FreeNAS?

Thanks