As noted by PC Magazine, a special BIOS update is being developed to fix a CPU lockup issue being experienced by AMD Ryzen chips which began to launch earlier this month.  

http://www.pcmag.com/news/352538/ryzen-7-chips-are-locking-up-pcs-amd-knows-why

All Ryzen desktop processors are suffering from the same problem, and owners are being asked to wait for BIOS updates to solve the issue.  AMD threw Intel a curve ball in February when the chip company announced its Ryzen CPUs would launch in early March. They are fast and significantly cheaper than Intel’s equivalent Core processors. It even led to some price cuts by Intel.

But with Ryzen chips now making their way into desktop PCs, AMD experienced its first major problem. All variants of the Ryzen 7 desktop processors are locking up PCs. The issue is related to FMA3 code, which are a set of streaming SIMD Extensions (SSE) that can greatly enhance the performance of floating point operations carried out by the chips. FMA3 isn’t new. AMD added support for the instruction set back in 2012.

Thankfully for Ryzen chip owners, AMD knows what the problem is but isn’t giving out much in the way of details. According to Digital Trends, the fix requires changes to the BIOS on motherboards. AMD is working on those changes, which will then be distributed to motherboard manufacturers who will then issue a patch.