There's a bug in the current revisions of X2 CPUs wherein either
the thermal safety throttling may be unexpectedly forced off, or wherein
its use could cause the CPU core voltage to spike, possibly frying the CPU.
If the thermal throttling is forced off e.g. in the BIOS as is suggested
as a "work-around" for this bug, it's possible that some BIOSs would permit
the CPU to continue to run continually even if it has reached temperatures
beyond which the CPU could be damaged; normally thermal
STPCLK speed throttling would reduce the CPU clock to prevent this
damage from being so likely.
If thermal throttling is NOT disabled as AMD suggests the BIOS does, *OR*
if user selected ACPI ower saving / utility functions triggers STPCLK
mode while the CPU clock is running at normal speeds, the voltage spikes
caused by the instantaneous 100 Watt <--> 0 Watt Vcore load change could
cause the system to spike or undervolt Vcore leading to either a crash
or very possibly a fried CPU!
Everyone should confirm with their BIOS vendor and settings for their
ACPI / thermal monitoring options in the BIOS that they're running the core
at safe temperatures and in a way that will not trigger STPCLK throttling /
power saving!
Here's the info from AMD:
http://www.amd.com/us-en/assets/con..._docs/25759.pdf
Revision Guide for AMD Athlon? 64 and AMD Opteron? Processors 25759 3.51 06/16/05
124 STPCLK Throttling Causes Violation of VDD_ac Specification
on Some Dual-Core Processors
Description
STPCLK throttling during maximum power consumption operation generates large load steps and voltage transients that can violate the transient
voltage specification (VDD_ac). This problem is exposed on 4-layer
motherboards with single power and ground planes when the
core frequency is >2000 MHz.
Potential Effect on System
Violation of the VDD_ac specification leading to unpredictable operation.
Suggested Workaround
Do not enable STPCLK throttling on affected dual-core processors above 2000 MHz.
Fix Planned: Yes
the thermal safety throttling may be unexpectedly forced off, or wherein
its use could cause the CPU core voltage to spike, possibly frying the CPU.
If the thermal throttling is forced off e.g. in the BIOS as is suggested
as a "work-around" for this bug, it's possible that some BIOSs would permit
the CPU to continue to run continually even if it has reached temperatures
beyond which the CPU could be damaged; normally thermal
STPCLK speed throttling would reduce the CPU clock to prevent this
damage from being so likely.
If thermal throttling is NOT disabled as AMD suggests the BIOS does, *OR*
if user selected ACPI ower saving / utility functions triggers STPCLK
mode while the CPU clock is running at normal speeds, the voltage spikes
caused by the instantaneous 100 Watt <--> 0 Watt Vcore load change could
cause the system to spike or undervolt Vcore leading to either a crash
or very possibly a fried CPU!
Everyone should confirm with their BIOS vendor and settings for their
ACPI / thermal monitoring options in the BIOS that they're running the core
at safe temperatures and in a way that will not trigger STPCLK throttling /
power saving!
Here's the info from AMD:
http://www.amd.com/us-en/assets/con..._docs/25759.pdf
Revision Guide for AMD Athlon? 64 and AMD Opteron? Processors 25759 3.51 06/16/05
124 STPCLK Throttling Causes Violation of VDD_ac Specification
on Some Dual-Core Processors
Description
STPCLK throttling during maximum power consumption operation generates large load steps and voltage transients that can violate the transient
voltage specification (VDD_ac). This problem is exposed on 4-layer
motherboards with single power and ground planes when the
core frequency is >2000 MHz.
Potential Effect on System
Violation of the VDD_ac specification leading to unpredictable operation.
Suggested Workaround
Do not enable STPCLK throttling on affected dual-core processors above 2000 MHz.
Fix Planned: Yes
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