One of the best features of the new AMD Ryzen CPU is that every processor is unlocked. That means no more “Black Edition” price premium, no K or X SKUs and for the most part unlimited overclocking potential. Of course, overclocking is dependent on several things including CPU quality (the bin), voltage and frequency options (the motherboard) and cooling capacity (your heatsink).
LN2 will give you the best thermal performance however, if the motherboard is voltage limited or comes with a rather small VRM you will likely have a bad time. The only real restriction is the chipset. X and B series chipsets are able to access the Ryzen unlocked multiplier so your choice in chipset comes down to if you need Multi GPU and care about overclocking.
Multi GPU: X3xx
Overclocking: X3xx / B3xx
My suggestion would be X370 every time.
At the time of the review Ryzen has been out for about a month and there are bound to be performance hurdles to overcome. AM4 friendly memory modules are in short supply and UEFI programming will need to be tuned to handle not only the new CPU but new memory modules and storage interfaces. Combine that with new drivers and OS support it will be a few months before things start to settle down.
As an overclocker I know that tuning just makes things smoother and it is how well the driver is programmed that will determine overall performance. I doubt there will be huge magical boosts in performance by simply installing a new driver but, it will help to make certain games run smoother considering that for the past 6 years the gaming and performance sector has been ruled by Intel.