Code:
(starting point)
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
7203 secs servo min: -71.800 uS max: 73.600 uS sdev: 3.500 uS
7203 secs servo min: -71.800 uS max: 73.600 uS sdev: 3.500 uS
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
7202 secs servo min: -74.000 uS max: 65.100 uS sdev: 4.200 uS
7202 secs servo min: -74.000 uS max: 65.100 uS sdev: 4.200 uS
(two runs, similar results, varying in +/- 3'000 to 8'000 nS, say roughly 10%)
(playing with isolcpus)
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=0,1"
7203 secs servo min: -75.900 uS max: 78.700 uS sdev: 3.800 uS
7204 secs servo min: -75.900 uS max: 78.700 uS sdev: 3.800 uS
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=1,2,3"
7200 secs servo min: -68.700 uS max: 65.700 uS sdev: 4.100 uS
7201 secs servo min: -68.700 uS max: 65.700 uS sdev: 4.100 uS
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=1,3"
7204 secs servo min: -65.200 uS max: 62.100 uS sdev: 3.700 uS
7205 secs servo min: -65.200 uS max: 62.100 uS sdev: 3.700 uS
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Bios version K01 v02.90, dated 07/16/2013
GRUB_CMDLINE_LINUX_DEFAULT="quiet isolcpus=2,3"
7199 secs servo min: -48.300 uS max: 44.500 uS sdev: 1.100 uS
7200 secs servo min: -48.300 uS max: 44.500 uS sdev: 1.100 uS
(A] best result so far, so use "isolcpus=2,3" from now on exclusively)
(starting to change bios version)
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Bios version K01 v02.98, dated 03/18/2015
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=3"
(mistyped "isolcpus=", got a real time delay, proof that it has an influence)
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Bios version K01 v02.98, dated 03/18/2015
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7203 secs servo min: -35.500 uS max: 34.500 uS sdev: 1.600 uS
7204 secs servo min: -35.500 uS max: 34.500 uS sdev: 1.600 uS
(B] already some 10'000 nS better than A])
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Bios version K01 v02.99, dated 09/15/2015
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7201 secs servo min: -24.500 uS max: 27.200 uS sdev: 1.300 uS
7202 secs servo min: -24.500 uS max: 27.200 uS sdev: 1.300 uS
(C] again some 8 to 10⁰000 nS better than B])
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Bios version K01 v03.02, dated 05/13/2016
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7202 secs servo min: -23.300 uS max: 28.100 uS sdev: 1.400 uS
7202 secs servo min: -23.300 uS max: 28.100 uS sdev: 1.400 uS
(D] similar to C])
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Bios version K01 v03.03, dated 07/14/2016
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7202 secs servo min: -26.600 uS max: 29.100 uS sdev: 0.800 uS
7203 secs servo min: -26.600 uS max: 29.100 uS sdev: 0.800 uS
(E] a bit worse, but imho conparable to C] and D])
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Bios version K01 v03.04, dated 10/05/2016
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7203 secs servo min: -25.500 uS max: 25.900 uS sdev: 1.100 uS
7203 secs servo min: -25.500 uS max: 25.900 uS sdev: 1.100 uS
(F] imho conparable to C], D] and E])
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Bios version K01 v03.06, dated 02/12/2018
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7200 secs servo min: -29.600 uS max: 32.100 uS sdev: 1.500 uS
7201 secs servo min: -29.600 uS max: 32.100 uS sdev: 1.500 uS
(G] a bit worse than C] to F])
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Bios version K01 v03.07, dated 05/10/2018
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7204 secs servo min: -34.300 uS max: 32.800 uS sdev: 1.800 uS
7205 secs servo min: -34.300 uS max: 32.800 uS sdev: 1.800 uS
(H] back to level of B])
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Bios version K01 v03.08, dated 04/10/2019
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet isolcpus=2,3"
7201 secs servo min: -25.700 uS max: 27.700 uS sdev: 1.500 uS
7202 secs servo min: -25.700 uS max: 27.700 uS sdev: 1.500 uS
(J] back to level of C] to F])