As an update to my post here, I observed seemingly random freezes on my system upgraded with the AMD FX-8350. The behaviour encountered was a total freeze of the desktop environment, no response to local keyboard nor mouse, no response to attempting to launch a virtual console, no reponse to pings over the network, and no ability to log in remotely. The only way to restore system operation was to perform a hard reset. Interestingly I could also consistently crash the system running a GraphicsMagick benchmark. Additionally, the freezes were OS-agnostic, occurring under both OpenIndiana and Ubuntu Linux.
Looking around online you can find several posts from folks on AMD Bulldozer rigs with very similar issues (such as detailed here), including a few from people who have rather alarmingly downgraded to a Phenom or Intel CPU as a “fix”, after having received advice to alternately update the motherboard BIOS, faff around with multiple BIOS settings, test and replace the RAM, power supply and hard disk, RMA-ing the new CPU (!?), and on and on and on. Most of this didn’t really add up, and similarly my problems were encountered on a system that was hitherto generally stable using an older-generation CPU (the Phenom II X6 in my case).
To cut a long story short, this quite simply turned out to be the motherboard not stably supporting the FX-8350. Although the ASRock 870iCafe 2.0 is an AM3+ compatible part and advertised as being “8 Core Ready” (to the point of specifically claiming compatibility with the FX-8350), the reality is that the latest BIOS release was in December of 2011 – a major red flag. After upgrading my motherboard to a Gigabyte GA-990FXA-UD3 with the recent F9 BIOS, the system is now stable. And yes, this is using the original PSU, RAM, graphics card etc.
For the OpenIndiana readers, the GA-990FXA-UD3 works fine, although don’t expect USB3.0 support: