Due to the fact we had only a couple of days with our sample and had some teething issues, we haven't been able to delve as much as we'd like into the overclocking side of things. However, it's not that complicated and with unlocked multipliers in abundance, if you just want a small boost then it will be as simple as raising the multiplier a notch or two, increasing the vcore and doing the usual stability testing.
One thing's for certain - temperature is not your friend with Ryzen, especially when you're dealing with all cores, which is our standard CPU test methodology as it provides the best performance in multi-threaded applications. AMD states that 1.45V is high limit for temporary benchmarking, but you'd need to be looking at lower than this for every day use. It also states that 4.2GHz should be achievable, but this wasn't so with our CPU, which was stable in some tests at 4.1GHz, but simply got too toasty during sustained multi-threaded loads with the needed vcore of 1.45V.
4.05GHz was again stable in all tests except Terragen 4's sustained load, and with the vcore reigned in to 1.43V too. In the end, we backed off to 4GHz - a 400MHz increase over the base clock, with applied to all eight cores under load, and used a vcore of 1.425V, which had temperatures in the mid 80's under full load using an NZXT Kraken X42. You'd need custom water-cooling to get noticeably better temperatures.
The EFI is one place to do battle using the FID (multiplier) and DID (divider) in a similar fashion to previous AMD platforms. For instance, to get to our 4GHz overclock, we used the standard D.O.C.P setting ratio (D.C.O.P is essentially the same as XMP on Intel boards - Asus calls it D.C.O.P but a Gigabyte AM4 board we've used called the profiles XMP, which is a tad confusing), a divider of x10 and multiplier 200.
AMD's Ryzen Master software is another. We're not entirely convinced our beta version was telling the truth half the time, so we used a mix of EFI overclocking and smaller tweaks in the software to get to our maximum overclock. However, we hope AMD continues to develop the software and iron out the bugs, because it makes overclocking Ryzen a pain-free process, with the ability to fine-tune each core a real boon too. We didn't have chance to fully explore the per-core overclocking side of things, but it's definitely worth looking at if you find a Ryzen system in front of you in the near future.