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HWBot benchmarks ban Windows 8 results because of dodgy RTC

by Mark Tyson on 20 August 2013, 15:45

Tags: Intel (NASDAQ:INTC), Windows 8, PC

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HWBot, one of the internet’s largest benchmarking and overclocking communities has banned Windows 8. Any benchmarks from systems running Microsoft’s latest operating system have been removed from community charts and league tables. The action has been taken “due to the severe validity problems with the Windows 8 real time clock (RTC),” explained a blog post on the community site.

Benchmarking tools use the Windows RTC as a reliable constant against which to measure a PC’s performance. The RTC in your PC should be as accurate as the quartz watch on your wrist for most benchmarking purposes. In most PCs the RTC is part of the southbridge and backed up with a small memory cell so it doesn’t forget the time while turned off. Unfortunately Microsoft made some changes to the Windows 8 RTC functionality as it saw that Windows 8 would be used in some low-cost and embedded systems without such clock hardware. The same is true in Windows 8.1 it has been revealed.

The RTC error is manifested if you change your CPU base clock in software after booting, then “it has a massive impact on Windows 8′s ability to keep accurate time,” reports ExtremeTech. Both overclocks and underclocks initiated from Windows have a massive impact on benchmark results. In HWBot’s testing it was found that underclocking a Haswell processor by six per cent after boot resulted in the Windows 8 RTC running a full 18 seconds slower than the actual time, within 5 minutes. The opposite effect was also observed; “When overclocking the base clock frequency, we can see the opposite effect. We overclock by roughly 4%, and after two minutes, Windows Time is 3 seconds ahead of real time” says the HWBot blog. As benchmarks measure a certain amount of operations over a fixed time period this is obviously a big problem in comparing benchmark results between systems.

Initially HWBot concluded that all Windows 8 systems were affected by this timing problem and decided to remove and not accept any benchmark results or records achieved under Windows 8. The community site explains that for all systems to be compared the RTC should be equal in all systems and Windows 8 raises too many question marks.

Systems which do and don't exhibit the RTC clock drifting problem

UPDATE: AMD systems running Windows 8 don’t have these RTC problems

In an update to the original blog post on the HWBot site today some more findings about the Windows RTC issue have been revealed. It appears that Windows 8.1 works in the same way, with regard to timekeeping, as Windows 8 so in that respect it’s no improvement. Looking at different processors and motherboard setups HWBot has also recently deduced that pre-LGA775 systems aren’t affected by this problem. Also AMD systems seem to be completely free of this clock-drifting issue under the tested circumstances.

HWBot will continue to provide updates on its investigations and says that more news will be published today. Perhaps the site will decide that AMD systems with Windows 8 will now be acceptable for inclusion in its charts and league tables.



HEXUS Forums :: 30 Comments

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Curiously, of course, what this bug actually does is make overclocked systems appear to take longer to do work, and underclocked system take less time. So it would cause Intel/Win8 systems to benchmark slower than expected when overclocked.

Makes you wonder what changes MS have made and why those changes *don't* impact AMD systems…
scaryjim
Makes you wonder what changes MS have made and why those changes *don't* impact AMD systems…
And how on earth they are ignoring the hardware RTC?! Yes, by all means have a back up for those systems that don't have one, but to ignore one when they're present in all desktop computers is just bizarre - everything in a PC should be timed from the initial hardware RTC so this is really grabbing at quite a deep level from microsoft (if it's them).
Moral of the story is buy AMD, and I already do!
However it does seem more like an error with the chipset than the operating system
sirtrouserpress
Moral of the story is buy AMD, and I already do!
However it does seem more like an error with the chipset than the operating system
Except RTC on the chipsets all work fine for windows 7, XP, linux etc.
It's about not reading the RTC because during the day they assumed that these frequencies wouldn't change. That is the problem. Not talking to the RTC makes things faster, and if you've got a clock of 200mhz +/-0.001% time keeping won't matter once it's been divided down in to the ticks.