[Bug 30349] GA-MA78G-DS3H (F9d) & Radeon 4730 system suddenly, but not quite randomly, softresets

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=30349

--- Comment #17 from Jouko Orava <jouko.orava at iki.fi> 2010-12-19 10:05:31 PST ---
As to mplayer, you can see if "-vo xv" triggers the problem if MCE is enabled
in the kernel; this is how I had mplayer configured. You could also install the
proprietary Catalyst driver, and see if you can reproduce the softresets. You
might have to try a lot of different graphics workloads, but if you can
reliably cause a softreset with Catalyst too, you can be pretty sure it's a
hardware problem.

Here's what I think (but remember this is just my humble opinion):

The root cause is a hardware problem, specifically a problematic voltage
regulator. In your case, the regulator is just borderline; disabling MCE causes
the motherboard to ignore the voltage drop; however, it's not outside the
working envelope for the northbridge chip, so the machine keeps working.

In my case, the voltage regulator failed in the span of a couple of weeks (from
completely OK to cracked and melted). Initially, disabling MCE avoided the
resets. Later, as the regulator degraded further, the voltage fluctuations most
likely caused the hardware CPU voltage protection to kick in, causing a reset.

The RS780 chipset is a complex beast. It's quite possible that a specific
workload -- not the heaviest one, but a specific type of workload -- stressed
the right voltage regulator (by requiring more current than otherwise). It
might be something as simple as a workload synchronized to the mains frequency,
or something esoteric like a PLL programmed to a specific frequency. I suspect
only a Gigabyte engineer can tell for sure.

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