A Timely Discovery: Examining Our AMD 2nd Gen Ryzen Results
by Ian Cutress & Ryan Smith on April 25, 2018 11:15 AM ESTAMD and Intel Have Different HPET Guidance
A standard modern machine, with a default BIOS and a fresh Windows operating system, will sit on the first situation in the table listed above: the BIOS has HPET enabled, however it is not explicitly forced in the operating system. If a user sets up their machine with no overclocking or monitoring software, which is the majority case, then this is the implementation you would expect for a desktop.
AMD
We reached out to AMD and Intel about their guidance on HPET, because in the past it has both been unclear as well as it has been changed. We also reached out to motherboard manufacturers for their input.
For those that remember the Ryzen 7 1000-series launch, about a year ago from now, one point that was lightly mentioned among the media was that in AMD’s press decks, it was recommended that for best performance, HPET should be disabled in the BIOS. Specifically it was stated that:
Make sure the system has Windows High Precision Event Timer (HPET) disabled. HPET can often be disabled in the BIOS. [T]his can improve performance by 5-8%.
The reasons at the time were unclear as to why, but it was a minor part in the big story of the Zen launch so it was not discussed in detail. However, by the Ryzen 5 1000-series launch, that suggestion was no longer part of the reviewer guide. By the time we hit the Ryzen-2000 series launched last week, the option to adjust HPET in the BIOS was not even in the motherboards we were testing. We cycled back to AMD about this, and they gave the following:
The short of it is that we resolved the issues that caused a performance difference between on/off. Now that there is no need to disable HPET, there is no need for a toggle [in the BIOS].
Interestingly enough, with our ASUS X470 motherboard, we did eventually find the setting for HPET – it was not in any of the drop down menus, but it could be found using their rather nice ‘search’ function. I probed ASUS about whether the option was enabled in the BIOS by default, given that these options were not immediately visible, and was told:
It's enabled and never disabled, since the OS will ignore it by default. But if you enable it, then the OS will use it – it’s always enabled, that way if its needed it is there, as there would be no point in pulling it otherwise.
So from an AMD/ASUS perspective, the BIOS is now going to always be enabled, and it needs to be forced in the OS to be used, however the previous guidance about disabling it in the BIOS has now gone, as AMD expects performance parity.
It is worth noting that AMD’s tool, Ryzen Master, requires a system restart when the user first loads it up. This is because Ryzen Master, the overclocking and monitoring tool, requires HPET to be forced in order to do what it needs to do. In fact, back at the Ryzen 7 launch in 2017, we were told:
AMD Ryzen Master’s accurate measurements present require HPET. Therefore it is important to disable HPET if you already installed and used Ryzen Master prior to game benchmarking.
Ultimately if any AMD user has Ryzen Master installed and has been run at any point, HPET is enabled, even if the software is not running or uninstalled. The only way to stop it being forced in the OS is with a command to chance the value in the BCD, as noted above.
For the Ryzen 2000-series launch last week, Ryzen Master still requires HPET to be enabled to run as intended. So with the new guidance that HPET should have minimal effect on benchmarks, the previous guidance no longer applies.
Ryzen Master is not the only piece of software that requires HPET to be forced in order to do what it needs to do. For any of our readers that have used overclocking software and tools before, or even monitoring tools such as fan speed adjusters – if those tools have requested a restart before being used properly, there is a good chance that in that reboot the command has been run to enable HPET. Unfortunately it is not easy to generate a list, as commands and methods may change from version to version, but it can apply to CPU and GPU overclocking.
Intel
The response we had from Intel was a little cryptic:
[The engineers recommend that] as far as benchmarking is concerned, it should not matter whether or not HPET is enabled or not. There may be some applications that may not function as advertised if HPET is disabled, so to be safe, keep it enabled, across all platforms. Whatever you decide, be consistent across platforms.
A cold reading of this reply would seem to suggest that Intel is recommended HPET to be forced and enabled, however my gut told me that Intel might have confused ‘on’ in the BIOS with ‘forced’ through the OS, and I have asked them to confirm.
Looking back at our coverage of Intel platforms overall, HPET has not been mentioned to any sizeable degree. I had two emails back in 2013 from a single motherboard manufacturer stating that disabling HPET in the BIOS can minimise DPC latency on their motherboard, however no comment was made about general performance. I cannot find anything explicitly from Intel though.
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andrewaggb - Thursday, April 26, 2018 - link
that MS link was very informative. Thankschrcoluk - Wednesday, April 25, 2018 - link
So the question is, What other things in the OS have you "tweaked" and not disclosed?peevee - Thursday, April 26, 2018 - link
This.Krysto - Wednesday, April 25, 2018 - link
Windows just release 2 new Spectre mitigations - make sure to include those, too.mode_13h - Thursday, April 26, 2018 - link
Any success replicating these results with their new BIOS/AGESA? Or is that a Linux-only fix?https://www.phoronix.com/scan.php?page=article&...
GreenReaper - Friday, April 27, 2018 - link
It may also cause a significant improvement in Raven Ridge performance:https://overclock3d.net/news/cpu_mainboard/agesa_v...
takeshi7 - Wednesday, April 25, 2018 - link
How do I check and/or change the OS-level HPET setting in Windows?I'd like to know if my system is in the forced-HPET mode.
Alistair - Wednesday, April 25, 2018 - link
run cmd prompt as an administratorbcdedit /enum
if there is a line like "use platformclock on" , then it is forced on
if no line, then it is off
BIOS is a "off" / "available" toggle, so there is no "on" in bios
JoeyJoJo123 - Wednesday, April 25, 2018 - link
I'm probably misinterpreting this, and feel free to correct me, but initial read of the title would suggest to the common user that "AMD Ryzen 2 has an issue with its internal timer", but upon reading, not only does Ryzen 2's HPET have a minimal performance hit compared to default behavior, but Intel's _own_ HPET is the variant with the LARGEST performance penalty.This information would imply that the Ryzen 2 benchmarks done so far only stand to gain a bit of performance (under default configurations), but nothing more than ~15% on very select game titles at 1080p, and less than ~5% elsewhere. (This is a good thing, as the good Ryzen 2 benchmarks only stand to gain a bit by measuring performance with HPET off.) It also then implies that Intel should likely be reviewing their HPET implementation to ensure that there's a minimal performance hit for applications which use this feature.
Ryan Smith - Wednesday, April 25, 2018 - link
"I'm probably misinterpreting this, and feel free to correct me, but initial read of the title would suggest to the common user that "AMD Ryzen 2 has an issue with its internal timer", but upon reading, not only does Ryzen 2's HPET have a minimal performance hit compared to default behavior, but Intel's _own_ HPET is the variant with the LARGEST performance penalty."Ultimately this article was a follow-up to our Ryzen 2 review, so it was necessary that it referenced it. (However the use of an Intel CPU picture was also very intentional)