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HPET - what evil may lurk in your BIOS?

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No application needs HPT,

HPT was introduced to give clustered servers a reliable system timer.

It is of no use on a windows PC and is less efficient which is why WIndows does not use it by default.

Turn it off in the bios and in windows unless you are running a server farm (unlikely )

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if HPET means High Precision Event Timer then applications do use it. I know because i've used it.

Gerry Howard

Most are saying if you have an older pc, then you might benefit from having it on, but beyond second generation i7, you might be better off disabling.

Can anyone with an Asus Sabertooth Z87 board tell me where this option is?  I can't find it for the life of me.

 

Regards,

Jay

Current Build (02/2024): AMD 7800X3D | Asrock X670E Steel Legend MB | Noctua NH-U12S Chromax | 32gb GSkill Trident Z5 DDR5-6000 CAS 30 | Samsung 990 Pro 2tb NVMe Gen4 (OS) | WD Black 4tb NVMe Gen4 (MSFS) | Corsair RM1000x Shift Series PS | ASUS RTX 4090 Strix ROG | LG 55" C2 Display

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Can anyone with an Asus Sabertooth Z87 board tell me where this option is?  I can't find it for the life of me.

 

Regards,

Jay

What makes you think you have it? Is High Precision Event Timer listed in your Device Manager in Windows? HPET is old technology AFAIK, maybe you don't have

Ric Elmore

 

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What makes you think you have it?

 

Paranoia? :unsure:

 

Seriously though, just reaching out to anyone with a Sabertooth Z87 board who can either confirm or deny it's existence because I can't find.

 

Thanks,

Jay

Current Build (02/2024): AMD 7800X3D | Asrock X670E Steel Legend MB | Noctua NH-U12S Chromax | 32gb GSkill Trident Z5 DDR5-6000 CAS 30 | Samsung 990 Pro 2tb NVMe Gen4 (OS) | WD Black 4tb NVMe Gen4 (MSFS) | Corsair RM1000x Shift Series PS | ASUS RTX 4090 Strix ROG | LG 55" C2 Display

Paranoia? :unsure:

 

Seriously though, just reaching out to anyone with a Sabertooth Z87 board who can either confirm or deny it's existence because I can't find.

 

Thanks,

Jay

 

You have it, it's under advanced then CPU Options, something like that. At the bottom it will say High Precision Event Timer.  That's how it is on the Asus Maximus VI Formula. 

David Graham Google, Network+, Cisco CSE, Cisco Unity Support Specialist, A+, CCNA

 

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Guys,

 

If you're running Windows 7 or later, the correct settings for this are the HPET *on* in the BIOS and bcdedit /deletevalue useplatformclock run from an elevated command prompt (this is the Windows default).

 

What this combination of settings does is allow the OS to use the CPU's invariant TSC (time stamp counter) if it has one (invariant TSC is is the more modern timing source that succeeded HPET). If the system doesn't have an invariant TSC it will automatically fall back on the HPET. You don't want to use a TSC that isn't invariant because it'll result in the different cores getting out of sync and the timing values fluctuating with clock speed when the CPU's power management functions kick in. HPET has high latency because it's external to the CPU (it resides on the southbridge chipset) which is why "disabling" it can help performance. If disabling it results in the use of an older TSC without invariance though, you're creating a bunch of potential problems far worse than some latency from calling out to the southbridge for timing information.

 

Article by an MS Windows kernel engineer explaining exactly how this all works:
http://performancebydesign.blogspot.pt/2012/03/high-resolution-clocks-and-timers-for.html

 

People really need to stop assuming Microsoft doesn't know what they're doing with deep core stuff like this - the OS already accounts for picking between an invariant TSC and the HPET as long as you're using 7 or 8/8.1, which I hope everyone here is.

Ryan Maziarz
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For fastest support, please submit a ticket at http://support.precisionmanuals.com

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Paranoia? :unsure:

 

Seriously though, just reaching out to anyone with a Sabertooth Z87 board who can either confirm or deny it's existence because I can't find.

 

Thanks,

Jay

I looked up the ASUS Z87 manual and there is no mention of HPET in the "Advanced\PCH" section of the BIOS. The Z77 has the aforementioned section . That's why I asked if you have HPET listed in your Windows Device Manager.

Ric Elmore

 

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As Tabs said, I get a bit better and smoother performance with HPET enabled in both BIOS and Win7.

Current system: ASUS PRIME Z690-P D4, Intel 12900k, 32GB RAM @ 3600mhz, Zotac RTX 3090 Trinity, M2 SSD, Oculus Quest 2.

Pe11e, Tabs didn't say to have it on in both. He recommended above that the best setting for Win 7 or later is to have it on in BIOS and off in win7 (bcdedit /deletevalue useplatformclock). That way it falls back on HPET anyway if it needs to.

 

I suppose that if we have a 64bit OS, we should make sure that HPET is set to 64 bit in BIOS? Mine was previously set to 32.

Why not just leave everything alone and use the default settings in BIOS and in Windows?

Um, JSkorna, the purpose of this topic is to determine what constitutes an optimal setting. If that optimal setting happens to coincide with the "default" for someone's particular motherboard, then your rhetorical question answers itself.

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people really need to stop assuming Microsoft doesn't know what they're doing with deep core stuff like this

 

This can't be emphasized enough.

 

Cheers!
 

Luke

Luke Kolin

I make simFDR, the most advanced flight data recorder for FSX, Prepar3D and X-Plane.

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