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#1
How do I raise the multi-core CPU limit?
Hello, I was just playing an extremely high-def video (1440p) using 64-bit VLC on my Windows 7 x64 ultrabook and it is stuttering. I checked Resource Monitor and it shows total CPU maxing out at between 25 and 30%. That raises the question: if Windows 7 thinks you have 4 cores, does it cap any particular process at 25% CPU? I'm using a dual-core Core i5 3317U, the most popular CPU in ultrabooks these days, which shows up as four cores in Resource Monitor because of hyper-threading. I can't seem to turn off hyper-threading in the aptio BIOS that comes with this ultrabook.
I have previously noticed that other processes that go out of control occasionally, like the Bluetooth monitor, will cap out at 25% CPU usage, but never figured out why till now. I thought that maybe it's a limit of each process only being able to max out a virtual core, but then I noticed that Resource Monitor shows all four virtual cores maxing out at 25% when running VLC with the 1440p video, as opposed to a single core maxing out at 100%. Does that mean that Windows 7 is emulating a single core limit by spreading the workload across each virtual core and capping each at 25% or is Resource Monitor lying to me and only one is maxed out?
I notice that if I open more VLC instances that play videos simultaneous to the 1440p video, the other 1080p videos play just fine, even though the 1440p video is still stuttering. Total CPU usage rises up to 50+% and all the cores show as sharing the workload relatively equally in Resource Monitor. I can see why this limit would be beneficial: the 1440p video is capped at 25% usage and doesn't affect the performance of the other videos, but I'd rather that the limit were higher.
Is there some way to raise this cap to 50% or more, so that a single process can use up to 50% of all four virtual cores? I checked my power settings and the processor maximum is set to 100%, so I don't think anything can be done there. If Windows 7 is really spreading the workload across all four virtual cores and setting an artificial cap of 25%, there should be a software setting where I can set the cap to be higher than 25% for a single process.