# HOW do I turn off High Precision Event Timer ??



## jonathan1107 (Mar 1, 2013)

How do I turn off HPET ??? It's nowhere to be found in my bios (asus sabertooth 55i)


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## jaggerwild (Mar 1, 2013)

Its in the Bios, mine is the third tab to the left in the new Bios.


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## jonathan1107 (Mar 1, 2013)

jaggerwild said:


> Its in the Bios, mine is the third tab to the left in the new Bios.



It is NOT an option in MY bios. Asus sabertooth 55i doesn't feature that option... Is there no way to turn it off IN windows 7 instead of the BIOS ?


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## Law-II (Mar 1, 2013)

jonathan1107 said:


> It is NOT an option in MY bios. Asus sabertooth 55i doesn't feature that option... Is there no way to turn it off IN windows 7 instead of the BIOS ?



Hi

May be have a look here - http://forums.guru3d.com/showpost.php?p=3770113&postcount=2

look under heading [Maximize your Windows timer resolution]

atb (all the best)

Law-II


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## itsakjt (Mar 1, 2013)

jonathan1107 said:


> It is NOT an option in MY bios. Asus sabertooth 55i doesn't feature that option... Is there no way to turn it off IN windows 7 instead of the BIOS ?



Just go to Device manager and expand the "System Devices" section. Look for High Precision Event Timer. Right click on it and click disable.. It should do the job.


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## Aquinus (Mar 1, 2013)

itsakjt said:


> Just go to Device manager and expand the "System Devices" section. Look for High Precision Event Timer. Right click on it and click disable.. It should do the job.



That disables the driver not the hardware that runs the HPET. You can only fully disable it through the BIOS. If you've looked everywhere it's possible that you might not be able to disable it.


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## Frick (Mar 1, 2013)

What is it?


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## Aquinus (Mar 1, 2013)

Frick said:


> What is it?



It's exactly as it sounds. A high precision event timer. It's supposed to be more reliable than programmable timers and the real time clock. It's basically dedicated hardware for hardware interrupt timers with a high level of precision and accuracy.



			
				Wikipedia said:
			
		

> The HPET can produce periodic interrupts at a much higher resolution than the RTC and is often used to synchronize multimedia streams, providing smooth playback and reducing the need to use other timestamp calculations such as an X86-based CPU's RDTSC instruction.



I also just looked through the manual for the Sabertooth 55i and there is no mension of the HPET. Maybe the board forces it to be on, in which case you're out of luck.

Why do you need to disable HPET anyways? It's best to keep it on.


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## Frick (Mar 1, 2013)

Ahh I see. And it causes problems how? I mean why would the OP want to disable it?


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## itsakjt (Mar 1, 2013)

Aquinus said:


> That disables the driver not the hardware that runs the HPET. You can only fully disable it through the BIOS. If you've looked everywhere it's possible that you might not be able to disable it.



I posted it because he asked if Windows has some way to do it. Maybe what he wants does not require to turn the hardware off. Also, a hardware is absolutely unusable if its drivers are disabled or not installed. So if the setting is not in the BIOS  the solution I posted is likely the best bet unless he physically destroys the HPET chip.


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## Aquinus (Mar 1, 2013)

itsakjt said:


> Also, a hardware is absolutely unusable if its drivers are disabled or not installed. So if the setting is not in the BIOS the solution I posted is likely the best bet unless he physically destroys the HPET chip.



Right, but the hardware is still active. It's possible that the chipset relies on it being on, so turning it off isn't an option.

Either way, I'm still curious why he needs it off in the first place. It's on the of the last things to cause problems on a modern machine.



Frick said:


> And it causes problems how? I mean why would the OP want to disable it?


I don't know. I would like to know this as well.


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## itsakjt (Mar 2, 2013)

Aquinus said:


> Right, but the hardware is still active. It's possible that the chipset relies on it being on, so turning it off isn't an option.
> 
> Either way, I'm still curious why he needs it off in the first place. It's on the of the last things to cause problems on a modern machine.
> 
> Exactly. I also wonder the same thing. In my old Pentium 4 rig, HPET was set to off. After I installed Windows 7, I was fiddling with the BIOS settings until I came to the HPET setting. The name somewhat told me what it really is. Then I turned it on and noticed a huge performance increase in the Windows Aero animations.


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## AsRock (Mar 2, 2013)

> Features
> 
> An HPET chip consists of a 64-bit up-counter (main counter) counting at a frequency of at least 10 MHz, and a set of (at least 3, up to 256) comparators. These comparators are 32- or 64-bit wide. The HPET is programmed via a memory mapped I/O window that is discoverable via ACPI. The HPET circuit in modern PCs is integrated into the southbridge chip.[note 1]
> 
> ...



http://en.wikipedia.org/wiki/High_Precision_Event_Timer

EDIT: Try looking under the ACPI bios options.


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## 95Viper (Mar 2, 2013)

Some have stated they have achieved reduced excessive latencies of Deferred Procedure Calls by disabling the High Precision Event Timer.
Making for smoother data streams and reducing drop out.

Some old, but, good reading here:  Guidelines For Providing Multimedia Timer Support

 A little how to dis-able and enable in windows:  DPC tweaking guide for AV / Gaming

And,  a quote from the BCDEdit /set command MS DEV web-page, where you can find usage for that command and others:



> The BCDEdit /set command sets a boot entry option value in the Windows boot configuration data store (BCD) for Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows Server 2012. Use the BCDEdit /set command to configure specific boot entry elements, such as kernel debugger settings, memory options, or options that enable test-signed kernel-mode code or load alternate hardware abstraction layer (HAL) and kernel files. To remove a boot entry option, use the BCDEdit /deletevalue command.
> 
> Caution  Administrative privileges are required to use BCDEdit to modify BCD. Changing some boot entry options using the BCDEdit /set command could render your computer inoperable. As an alternative, use the System Configuration utility (MSConfig.exe) to change boot settings.


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## jonathan1107 (Mar 2, 2013)

Thanks for the input guys. I'm trying to disable the HPET setting and maxing my Timer Resolution as well as disabling core parking to maximize SLI performance...

HPET is known to cause instability and some fps drops in SLI setups... at least so I've read on many different forums. That is why I wanted it disabled ... I also read somewhere that you can set the system to use the HPET "ONLY" which also results in an increased performance, not sure which is better (HPET only vs HPET off) will have to test and see which gives me the best DPC latencies...

Link to HPET disabled recommendation: 
http://forums.guru3d.com/showpost.php?p=3770113&postcount=2

HPET ONLY source (quote): "HPET is mostly used for multimedia / syncing media streams with audio. If you disable it, the OS / app if it uses falls back to RTC and may start desyncing video. I can't really think of a good reason to disable it unless your systemboards implementation is crap (it happens). You also may need to force Windows (no idea on Linux) to only use HPET so the CPU isn't wasting time syncing all the rest of the system timers.

bcdedit /set useplatformclock true (then reboot) enable HPET
bcdedit /deletevalue useplatformclock (then reboot) disable HPET

Mileage varies like all changes to computers" (quote end)


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## LAN_deRf_HA (Mar 2, 2013)

I can't even turn it on if I wanted. Nvidia won't fix the Asus/SLI/HPET bug and it's been years since it started.


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## jonathan1107 (Mar 3, 2013)

Hi, you mentionned I should look under ACPI options to find my HPET settings in my MOBO menu...

"EDIT: Try looking under the ACPI bios options."

When I look in the ACPI options I'm given a few:

take a look @ the screenshot of my MOBO manual here 




image hosting sites

which setting should I change ?


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## erocker (Mar 3, 2013)

After doing a google search, it seems as if you have no HPET option in your bios. https://www.google.com/search?q=Sab...75,d.dmQ&fp=a81f7da92f51477&biw=2560&bih=1294

From what I've read, there's no reason to turn it off.


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## jonathan1107 (Mar 3, 2013)

erocker said:


> After doing a google search, it seems as if you have no HPET option in your bios. https://www.google.com/search?q=Sab...75,d.dmQ&fp=a81f7da92f51477&biw=2560&bih=1294
> 
> From what I've read, there's no reason to turn it off.



well the ACPI APIC setting seems to be the right setting to disable, since it mentions high precision interrupts... which is the closest thing I've found to HPET...

I was told by many to disable it for crysis 3, especially in SLI config... apparently it reduces the DPC latency by a lot...

also, I have to disable core parking...

I just can't believe how crazy crysis 3's FPS is... I'm playin in the 1st mission on the ship, and whenever I face a window and look far off the fps drops to 20fps (with a 670 sli setup LOL)... so is it just me or this game is CPU hungry (unoptimized) ?

with a BEAST pc like mine I would have hoped for better FPS in crysis 3. I've been trying different tweaks, still can't get a solid 60fps... Crysis 3 feels like skyrim (because the FPS is solid 60 and drops to 20ish when just looking in a certain direction in certain areas...)

or could it be my CPU bottlenecking my GPUs... ?


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## Aquinus (Mar 4, 2013)

jonathan1107 said:


> I was told by many to disable it for crysis 3, especially in SLI config... apparently it reduces the DPC latency by a lot...



I've heard this too but I think this is an old issue. I would be very surprised if this is the case now and if it is. Also I doubt that disabling power states won't do it since this is a chipset specific feature where interrupts other than just low power modes rely on the HPET.

I would setup MSI Afterburning to output Framerate, both GPU temps, and both GPU usages to the OSD and I would see how load changes according to frame rate. I can't give you a comparison because I haven't played Crysis 3, and unless it's significantly different from the first two, I'm reluctant to buy it.



jonathan1107 said:


> with a BEAST pc like mine I would have hoped for better FPS in crysis 3. I've been trying different tweaks, still can't get a solid 60fps... Crysis 3 feels like skyrim (because the FPS is solid 60 and drops to 20ish when just looking in a certain direction in certain areas...)



Heh. Arrogance, I love it! I'm just kidding. I understand loving one's machine. I love mine, but in all honestly, the only beastly thing about your machine is your 670s in crossfire. As far as memory and CPU speed is concerned, the i7 875 @ 4Ghz isn't bad, but you have new architecture chips pumping out higher numbers without water. My i7 3820 for example is running at 4.5Ghz on air and memory is at 2400Mhz (4 channels of it,) as well as two SSDs in RAID-0 and 3 HDDs in RAID-5. Which would be more "beastly" than what you got, but the 670s waltz over my 6870s. Granted I only game occasionally. My video cards probably crunch more than they game.

So as beastly as your rig is, it's not completely beastly and now that you mention it, it doesn't hurt to make sure your CPU isn't bottle-necking as well. Occasionally my i7 3820 will bottleneck on a game, but it's usually pretty rare and it's usually due to not being multi-threaded all that well. I don't expect this to work, by try setting your power options in Windows to "Performance". That way we know your CPU isn't going into a low power state so we can rule that out.


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## jonathan1107 (Mar 4, 2013)

Aquinus said:


> I've heard this too but I think this is an old issue. I would be very surprised if this is the case now and if it is. Also I doubt that disabling power states won't do it since this is a chipset specific feature where interrupts other than just low power modes rely on the HPET.
> 
> I would setup MSI Afterburning to output Framerate, both GPU temps, and both GPU usages to the OSD and I would see how load changes according to frame rate. I can't give you a comparison because I haven't played Crysis 3, and unless it's significantly different from the first two, I'm reluctant to buy it.
> 
> ...



my power states are disabled (my CPU OC is a constant OC) the only thing I can rule out now, is the core parking...

and yes, I'm very aware that my PC ain't the very best out there. this is my 1st build ever, and I made a lot of dumb mistakes thinking I was actually buyin the best stuff until I learned even more about computers and whatnot later...

And so my next 2 upgrades will be my CPU and Mobo, but heck... with 2x 670s in SLI, with a rig like mine, there's just NO way the fps can be that low... it's 800$+ worth of GPU horsepower lol... Believe me, the game ain't well optimized... The Witcher 2 has just as much eye candy, and a single 670 runs it Maxed...


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## Aquinus (Mar 4, 2013)

Well, it sounds like there is a bottleneck to me. I seriously doubt that HPET is causing this. Like I said before, I would watch usages while you're gaming to see if your topping out the CPU or GPUs. Weather or not it seems obvious or not, it's a place to start and until you test it you'll never really know.

Also the hardware in your rig looks fine, unless you've been doing what I used to do and just constantly replace parts.  I'm glad that I finally have a platform that I'm happy with though.


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## jonathan1107 (Mar 5, 2013)

Aquinus said:


> Well, it sounds like there is a bottleneck to me. I seriously doubt that HPET is causing this. Like I said before, I would watch usages while you're gaming to see if your topping out the CPU or GPUs. Weather or not it seems obvious or not, it's a place to start and until you test it you'll never really know.
> 
> Also the hardware in your rig looks fine, unless you've been doing what I used to do and just constantly replace parts.  I'm glad that I finally have a platform that I'm happy with though.



Being that I use EVGA precision X, I cannot monitor my GPU usage (at least not with itself)... what can I use to monitor CPU usage?


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## LAN_deRf_HA (Mar 5, 2013)

Why can't you monitor gpu usage in precision?


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## jonathan1107 (Mar 5, 2013)

dunno... might have to do with the k-boost feature


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## Basic (Oct 20, 2013)

*All about timing*

There really aren't many reasons to disable the HPET and a lot of good reasons not to.

If you're really interested in that goes on under the covers, have a read  of this (warning it's pretty technical).

The short 'n simple version is that although a thread can query the time at relatively high accuracy, the shortest period of time it can release context and wait is controlled by the hardware interrupt frequency. For most systems without an HPET, this is on the order of ~15ms (huge oversimplification).

Having an HPET (or even better, an invariant TSC [Timestamp counter]) increases that frequency from the millisecond range to the microsecond range. TSC and HPET tend to be less susceptible to thermal drift too, meaning more consistent interrupts.

The factors controlling interrupt frequency are many and varied - from the OS version, through motherboard, CPU and BIOS support so my limited explanation above glosses over a _lot_ of detail.

Hope that helps and apologies if adding a definitive resource is seen as necroing...


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