Gamer's perspective:
http://www.mikemartin.co/system_guides/hardware/motherboard/disable_high_precision_event_timer_hpet

RE: bcdedit  /set useplatformclock true (tweak)...
Full Disclosure: I have, in previous posts advocated for this tweak.
 
After a lot of research and testing I am back to report as promised.
 
Program I used to check deferred procedure calls was DPC Checker.
Monitored the CPU with CPUID.
Motherboard is same as in sig, an Asus Sabertooth Z77(very good board).
Processor: i7 2600k.
Memory: 32gb DDR3 memory at 1600.
 
I tried numerous configurations with HPET on/off, C states on/off, TurboBoost on/off.
I kept Core Parking off throughout testing.
 
...The long and short of it is that I got more of a placebo effect from initial testing than
I was willing to admit.
 
DPC never got below 145 nanoseconds no matter what configuration I tried with HPET on,
with spikes as high as 1500 nanoseconds under heavy loads.
I also experienced several random crashes to Restart which has never occurred previously.
 
With HPET off, and TurboBoost and C states on, DPC range went to 45-125 under all loads.
With HPET off, and TurboBoost and C states off, DPC range was 25-145.
 
However; I found that my lowest DPC range of 25-45 occurred, under ALL loads when
using the X.M.P. Memory Timings built in to my ASUS board, along with
keeping HPET, C states and TurboBoost off.
 
This is my present Configuration and it's working great with Foxboro.
I promised an honest review, and here it is.
 
This is just MY opinion on MY system, and henceforth I neither advocate for or discourage it's use.
 
Make your own tests and use your own judgments.
 
Mel
 
 
EDIT: I forgot to mention that my MB has an HPET setting which defaults to ON,
         which I left that way throughout testing, so no, I did not test with HPET Disabled
         on the motherboard.

OldTimerNewComer
However; I found that my lowest DPC range... under ALL loads when
using the X.M.P. Memory Timings...along with
keeping HPET, C states and TurboBoost off.

 
My system performs with the lowest DPC latency when doing the same as you posted in the excerpt I quoted of your post. (My system specs: Core i7 920 @ 2.66 GHz, Gigabyte EX58-UD5,24GB 1333MHz DDR3 @1333 MHz).
 
Something I found that is interesting with my system is that under heaviest loads running with an ASIO buffer setting of 8.71 ms at 44.1/16, DPC Latency Checker shows readings in the range of 21us-10us, but if I lower the ASIO buffer setting to 5.80 ms at 44.1/16bit, DPC Latency Checker shows readings in the range of 100us-74us. Playback is smooth at either ASIO buffer setting size (with no dropouts, pops, or stuttering, etc). I guess the strain that the lower buffer size puts on the CPU causes the higher DPC latency readings. I didn't expect higher readings. I expected lower readings. I find the higher readings (because I lowered the ASIO buffer setting) to be interesting.
 
EDIT:
 
To clarify, I had HPET off. You may get lower DPC latency readings if you turn off HPET.

I reloaded this machine from scratch a week ago and saw similar (also ASUS with same CPU). For me I set XMP to 103, HPET enabled, Turbo enabled, core parking (all power options) disabled (in system). HPET comes up automatically in the system. I think this is really more a system by system thing. XMP was the only real BIOS change over "defaults."

Overall common things seem to be disabling core parking/power management, and disabling services with automatic functionality - win search, LAN auto detects - again is something to verify/adjust on a system basis.

thomasabarnes

OldTimerNewComer
However; I found that my lowest DPC range... under ALL loads when
using the X.M.P. Memory Timings...along with
keeping HPET, C states and TurboBoost off.

 
My system performs with the lowest DPC latency when doing the same as you posted in the excerpt I quoted of your post. (My system specs: Core i7 920 @ 2.66 GHz, Gigabyte EX58-UD5,24GB 1333MHz DDR3 @1333 MHz).
 
Something I found that is interesting with my system is that under heaviest loads running with an ASIO buffer setting of 8.71 ms at 44.1/16, DPC Latency Checker shows readings in the range of 21us-10us, but if I lower the ASIO buffer setting to 5.80 ms at 44.1/16bit, DPC Latency Checker shows readings in the range of 100us-74us. Playback is smooth at either ASIO buffer setting size (with no dropouts, pops, or stuttering, etc). I guess the strain that the lower buffer size puts on the CPU causes the higher DPC latency readings. I didn't expect higher readings. I expected lower readings. I find the higher readings (because I lowered the ASIO buffer setting) to be interesting.
 
EDIT:
 
To clarify, I had HPET off. You may get lower DPC latency readings if you turn off HPET.

I will give that a try...
Every little bit helps.
 
Mel

Just a bootnote.
I did a wipe and clean a clean Windows 10 installation with HPT enabled in the BIOS.
Windows 10 enabled High Precision Event Timer in device manager by default.