This post explains what to do when your Windows 8 with Hyper-V enabled laptop has power issues.
Symptom:
While working on a light or heavy workload the laptop turns off. I do not mean shuts down or blue screens but acts as if you just pulled out the battery and power cord at the same time. Basically, a turned off laptop where a running one once was. I have been battling this intermittent issue on my Dell Latitude E6420 laptop for the last year. Sometimes it was twice in a day, sometimes it was once a week, other weeks were totally clean. Dell support believed it was an issue with the motherboard (twice). At one point, I believed it was an issue running Windows 2008 R2 on a laptop but that is a story for another post. When the problem happened on a fresh Windows 8 install it got me thinking.
Resolution:
Windows 8 ran totally clean for a month before the power kill happened. Right about the time I turned on Hyper-V, hmm... A few Google searches later and I had the solution. In the BIOS, Virtualization Technology needs to be turned on and VT for Direct IO will be needed for some functionality.
Cause:
Hyper-V does not play well with Intel's C-States. C-States are low power modes for CPUs (see references below for more info). This doesn't make much sense for a server in a data center, especially when it runs multiple VMs so turning them off is a good thing. Turning them off will also give your server better performance. In Hyper-V's defense, they aren't the only one to suffer issues from C-States. XenServer has had well documented issues (CTX127395) as well.
Sidenote: I did not find official recommendations from Microsoft to turn it off because of issues but I did find one to turn it off for better performance.
SageLike Post ID: SL0002
Applies to:
Windows 2008 R2
Windows 8
Maybe others
References:
hardwaresecrets.com - Everything You Need to Know About the CPU C-States Power Saving Modes
technet.com - Hyper-V and BIOS power plans (c-states)
KB974598 - You receive a "Stop 0x0000007E" error on the first restart after you enable Hyper-V on a Windows Server 2008 based computer
KB2000977 - Hyper-V: Performance decreases in VMs on Intel Xeon 5500 (Nehalem) systems
CTX127395 - Hosts Become Unresponsive with XenServer 5.6 on Nehalem and Westmere CPUs
CTX130464 - How to Check if Extra C-States are Enabled without Booting into the BIOS.
SL0002 - Windows 2008 R2 on a Laptop
