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AMD C1E support and time drift...

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solstice

Member
Joined
Dec 6, 2008
I was debugging my system why clock drifts occurs so badly. It has gotten to a point that I have to update every 30 minutes in order to update clock every 30 minutes to correct shift in clock that is more than 3 minutes delta. What I noticed recently is that the clock drift does not occur in the bios and only occurs in the VISTA. So I start playing around with various bios parameter until I hit the C1E bios options. It turns out this option created my clock drift problem. Ironically, this only started because I am trying to cut normal power consumption when I don't need the speed and over clock when I do.

In any case, have anybody notice similar thing with enabling AMD C1E and Windows VISTA with clock drifts? If not, I hope my experience will help other whom may have similar problems.
 
Can you explain Clock Drift in more detail, I don't understand what you mean but I think I do.
 
C1E is a power saving feature, enabling it should allow large fluctuations in clock speed, and even voltage IIRC. Are you saying that your target speed fluctuates when it ramps back up? If you're talking about overclocking with C1E on, it will definitely fluctuate if you're trying to maintain an over-volted overclock, because the BIOS will not auto feed the amount of voltage required to maintain an overclock. The same as moving your voltage CPU voltage off of auto, when trying to overclock, it can't automatically provide what is needed. Please disregard if this is not what you're speaking of.
 
Sounds to me like he's saying his system clock is experiencing a high rate of skew when C1E is enabled.

Aka, with C1E enabled and his clock showing 2:30 PM, it might show 2:27 PM or 2:33 PM by the time 30 *real* minutes elapse.
 
Sounds to me like he's saying his system clock is experiencing a high rate of skew when C1E is enabled.

Aka, with C1E enabled and his clock showing 2:30 PM, it might show 2:27 PM or 2:33 PM by the time 30 *real* minutes elapse.

Ah! you're right... a quick reread, and I see I jumped past a few things. Delta would have been a give away :-/ Like I said... please disregard if this isn't what you're speaking of :) Good catch Particle.
 
Sounds to me like he's saying his system clock is experiencing a high rate of skew when C1E is enabled.

Aka, with C1E enabled and his clock showing 2:30 PM, it might show 2:27 PM or 2:33 PM by the time 30 *real* minutes elapse.

Yep, that is what I meant. Basically I sync at 2:30PM, by real world clock at 3:00PM, my computer would display 2:55PM. A whole 5 minute shift in clock!

It is a weird problem and I have no idea why.
 
AMD and MS (yes, they actually admitted there was a problem!) are still working on some issue with C1E and Vista. This may be one of the problems they were having. I don't know how far they've come to fixing all the issues - the article I read was several months old ...
 
Baha, got to love those posts... But what exactly is C1E? It sounds like C'n'Q from my brief read of this thread, so why not use C'n'Q?
 
CnQ works by lowering the CPU multiplier and vCore, so the whole CPU goes into a slowed-down mode, usually half the speed of normal.

C1E works on individual cores. It flushes the core's L2 cache into L3 in case there's any data another core might need, then it puts that core into a deep sleep. The difference is the others cores are still running and computing normally. On a quad this means, at the far end, only one core is running while the others are virtually turned off - which is quite a power savings. There's also a lot less heat so a rig using SmartFan too would see a big drop in noise levels as well ... :)
 
CnQ works by lowering the CPU multiplier and vCore, so the whole CPU goes into a slowed-down mode, usually half the speed of normal.

C1E works on individual cores. It flushes the core's L2 cache into L3 in case there's any data another core might need, then it puts that core into a deep sleep. The difference is the others cores are still running and computing normally. On a quad this means, at the far end, only one core is running while the others are virtually turned off - which is quite a power savings. There's also a lot less heat so a rig using SmartFan too would see a big drop in noise levels as well ... :)

Well, thanks for the explanation... I'm guessing just on the PII's?
 
Created a membership here just so I could mention this:

http://lwn.net/Articles/286432/

It appears you may have a choice, at least if you own an Asus motherboard: you can either disable C1E support, or disable "HPET" support. That latter enables or disables the high-precision timers that Vista (alone) uses, which someone else mentioned. It may be that disabling HPET in the CMOS will allow use of C1E with Vista at this time; that is the implication of that message. I haven't and can't try it to confirm, since I don't use Vista, but the options I mentioned exist even on my M2N-SLI Deluxe AM2 motherboard (upon which I am about to mount one of the AM2+ CPUs it now supports). I found this thread as a result of reexamining my CMOS config prior to installing the new CPU, and couldn't recall the relevance of C1E.
 
Created a membership here just so I could mention this:

http://lwn.net/Articles/286432/

It appears you may have a choice, at least if you own an Asus motherboard: you can either disable C1E support, or disable "HPET" support. That latter enables or disables the high-precision timers that Vista (alone) uses, which someone else mentioned. It may be that disabling HPET in the CMOS will allow use of C1E with Vista at this time; that is the implication of that message. I haven't and can't try it to confirm, since I don't use Vista, but the options I mentioned exist even on my M2N-SLI Deluxe AM2 motherboard (upon which I am about to mount one of the AM2+ CPUs it now supports). I found this thread as a result of reexamining my CMOS config prior to installing the new CPU, and couldn't recall the relevance of C1E.

I tried disabling the HPET before I disabled the C1E and that did not fix the problem. The only one that worked fairly well was disabling the C1E.
 
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