Originally Posted by Aquinus
It might not need it. More and newer VRMs probably produce less heat because they're newer and more refined and because distributing the CPU power load across more phases will reduce the load on each one which will drive efficiency up and heat down. In addition to generating less heat its more surface area that a heat sink can cover so you're moving more heat away as well. Very interested to see who this board overclocks and what price ASRock is looking to put it at. It looks pretty solid to me.
This appears to be the same basic 12+2 VRM design as the Asrock 990FX Fatality mobo which has been around for awhile. They claim to be using stacked MOSFETs which may or may not be ideal for cooling of the VRM. Virtually all AM3+ mobo VRM circuits run very hot with overclocked 8-core FX processors so good VRM cooling - either passive or with fan is required. This mobo and the Fatality model use large passive heatsinks which are preferred for reliability and noise, IMO.
Every quality mobo I have seen in recent years has a VRM thermal throttle that lowers the CPU voltage and frequency if the VRM circuit is running too hot. This is sort of a half-arsed solution for insufficient VRM power capacity when needed, with seriously overclocked CPUs, especially 8-core FX models. Some mobo VRM circuits still burn out as they are really poor designs and should not even be sold in their current state for 125W+ CPUs.
I contacted Asrock to inquire what was better about the Extreme 9 vs. the 990FX Fatality and they couldn't answer. Other than some minor tweaks it's pretty much the same mobo. If you need the slight differences or the price is lower than the Fatality 990FX, then this might be the mobo for you. Otherwise it's pretty much more of the same, which is fine as there is nothing wrong with the 990FX Fatality mobo IME.