Windows 10 Affected By Same Downclock Bug Like Windows 8/8.1, Disallowed For Now

Microsoft recently released a Technical Preview of its upcoming Windows 10 operating system. We had a quick look at the operating system to find out it still has the same underclocking bug as their previous two operating systems. The benchmark veracity is in other words still compromised and there is currently no other option than to disallow Windows (10) Technical Preview for submissions at HWBOT.

To recap the problem, here's an excerpt from our Windows 8 article:

“The concept of ‘time’ on a PC configuration is, if not synced via network or internet, an arbitrarily defined constant designed to ensure that the configuration is running in sync with the real world. In other words: hardware and software engineers ensure that ‘one second’ on your PC equals ‘one second’ in real time. One of the reasons why it’s so important to have the PC’s timer line up with the real world time is to ensure that your PC can produce accurate measurements and predictions.” The points we brought up in that editorial are relevant again. To ensure that the arbitrarily defined constant of ‘time’ is the same on everyone’s benchmark system, we rely on the OS and hardware. This worked quite well, until Windows8 came around.

The problem builds on the problems we faced with Heaven. When downclocking the system under Windows8, the Windows RTC is affected as well. The biggest difference between Windows7 and Windows8 is that now all benchmarks (no exception) are affected.

Let us make this more practical. On our Haswell test system we downclocked the BCLK frequency by about 6% from 130 MHz to 122MHz. Using a CPU ratio of respectively 32x and 34x, the resulting CPU frequency remains 4160MHz. Then we ran comparison benchmarks.

We ran a quick test to verify the problems using SuperPI 1M. Below you can find a table with the information.

BCLK frequencyCPU RatioOperating FrequencyBenchmark score
100 MHz40x4000 MHz9.079 sec (reference)
102.5 MHz39x4000 MHz9.282 sec
97.56 MHz41x4000 MHz8.870 sec

As you can see from the above table, lowering the BCLK frequency while maintain the same operating frequency results in a "faster" benchmark time. Increasing the BCLK frequency while maintaining the same operating frequency results in a "slower" benchmark time. This is identical to the behavior we are seeing in Windows 8 and Windows 8.1.

For reference we also made a video showing that the system timer is running out of sync. For this video we underclocked the base clock frequency from 100 MHz to 98 MHz. After 8 minutes and 50 seconds, the system is lagging behind about 8 seconds.


Italy Atlas Rush says:

Thanks for informing us! I installed the TP just yesterday and I was wondering about the bug!
Since I'm into the Insider Program (and all of us that are using it are) I could try to report this bug :)

K404 says:

It's not a bug, it's a feature :(

Germany SoF says:

[QUOTE=James May (Cpt.Slow)]"Oh c*ck not again..."[/QUOTE]

Still know about the days MS fixed importants bugs in the next version and not told overclockers "we did it in windows 9(.X)" ...pepperidge farm remembers...

Canada Vinster says:

only way to get it fixed is to have Intel/AMD report a loss in revenue from enthusiast... but there aren't enough of us to make a real dent.

Czech Republic buildzoid says:

Vinster said: only way to get it fixed is to have Intel/AMD report a loss in revenue from enthusiast... but there aren't enough of us to make a real dent.

Not gonna happen most of us will just keep a win 7 install. Look at XP everyone who is serious about SuperPi uses win XP and XP no longer gets any support.

Belgium Massman says:

I don't really expect Microsoft to fix anything ... Unless we all move to Linux and show the world there's another platform for the having the best gaming platform

Canada Vinster says:

I'd love to try some of this on Linux. Wonder how easy it would be to port/create some of the benches over.

Windows games apparently work on Linux now (with the right add-on's), only a few mild hurdles to overcome and I'll be dedicated shortly if things continue to improve as they are.


Norway knopflerbruce says:

Linux will turn things around :p tweaker's dream I think. And moderator's nightmare.

GENiEBEN says:

knopflerbruce said: Linux will turn things around :p tweaker's dream I think. And moderator's nightmare.
There's not much to tweak other than dumping the DE and recompiling kernel with all extras out, and flags for your platform.

Germany AwardFabrik says:

Had some tries with vine some time ago and I can tell you... Linux is a great benching OS....said no bencher ever ^^ €: oh lol looks I got a new account xD €²: I was working within MSDN 10 years ago and things have been much easier back then... I can't imagine it's just the scores/times within OC go nuts but some time measurement-related software etc must be affected as well?!

Canada Vinster says:

Just saying, read about Steam working on Linux and then there is support for windows games (Using Wine if they have that, what's stopping someone from benching anything futuremark? DX/OpenGL... I think it might be worth a side partition. just wish I had time and a spare disk for my production pc for some testing. Sorry for getting off-topic, but sort-of relevent

Poland DeathRabit says:

When I used OC at FSB 140 Windows 10 time shift was noticeable * after few hours in use shit was around 2-3 hours.

United States Splave says:

z170 this is fixed, you can try it

United States rtsurfer says:

[strike]If only Hwbot had implemented/accepted a 3rd party monitoring tool. How many new/causal people deter from overclocking because they can't use their regular OS.

Maybe they should fix that while trying to "promote" overclocking. [/strike]

NVM, just saw this

I guess they are working on it. Thank god.

GENiEBEN says:

rtsurfer said: I guess they are working on it. Thank god.
Expect something by Monday ;)

United States Random says:

Thats lame. I had to upgrade my 8 cuz it was borked, and 7 isnt allowed in fse and xtu for whatever brilliant reason

websmile says: Cough - who said 7 is not allowed at xtu and fse? We would have to delete 50% + of all results :D - of course you can use 7 :)

United States Random says:

In the rules for a few of the benches it says windows 8 versions only, i forget which ones.
Fse, geekbench, or xtu, one of the ones ive been doing lately...
Lol whoops, i read the opposite, is says those aren't allowed.. damn skimming...
Looks like i have some benches to rerun

websmile says:

win 7 usually is always allowed, on win8 and now 10 there are restrictions like validation link and sys info above 4.20 used, this is clarified at rules. Happy re-benching, Matt :D

United States Random says:

oh well I was just complaining about how I had nothing to do till SK, or 980Ti KPEs get back in stock..

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