Vista - *SpeedStep Guide:*

This is a little FAQ on C1E, EIST and SpeedStep in general. Since this question gets asked so much, I thought it would be a good idea to post a definitive answer on the subject.

Why is my processor running slower than I told it to in the BIOS?

This question is perhaps the most commonly asked of all in the world of OCing.
Many young overclockers eagerly increase their BIOS settings, only to boot into Windows and find that their CPU is considerably slower than it should be.
On top of that, its speed jumps up and down. What causes this phenomenon, and how can it be fixed?

The issue at work here is thanks to Intel's SpeedStep technology - a handy feature implemented in all of their new CPUs. SpeedStep is a function that detects how much work your processor is doing, and lowers or raises its speed based on that reading. This means that when your processor is idle, or performing simple tasks like browsing the Web, it will run slower. When it's benching, stability testing, gaming, video encoding and such, its speed drastically increases to provide the best performance. Let's look at an example:

You've set your machine up to run with an FSB of 450, and your processor has multipliers between 6 and 9. While idle, your processor will run at 450 * 6 = 2.7 GHz. Under load, it will automatically boost up to 450 * 9 = 4.05 GHz! That's a huge difference, and you can see why it can be useful. 4.05 GHz is a considerable speed to achieve on any processor, and takes a lot of power to run. When you're checking email, you don't need 4.05 GHz of speed, so SpeedStep lowers it to a lesser state.
This way, your system saves power, runs cooler, and puts less strain on all of the components - meaning that they last longer.

Let's look at how it works. SpeedStep has two key components:

C1E (Enhanced Halt State): C1E is the simpler of the two components. It can be enabled or disabled in the BIOS, and performs independently of the operating system. C1E has two configurations - idle, and load. When CPU usage is relatively low, this feature lowers your processor's multiplier to its lowest setting (usually 6x) and slightly lowers its vCore. During a CPU-intensive application, it will raise the multipler to its maximum value, and will provide a small boost in vCore to compensate. In our example, C1E will make your processor run at either 6x or 9x the FSB.

EIST (Enhanced Intel SpeedStep Technology): This is a very robust feature and has a wide variety of power-saving capabilities. Like its simpler cousin, EIST can affect both your CPU's voltage and it's multiplier - however, it has many more levels of configuration. Instead of a simple "slow or fast" setting, SpeedStep can utilize all of the available multipliers. In our example case, EIST will allow your processor to run with a multiplier of 6, 7, 8, or 9, and chooses which one to use based on how much demand your CPU is under. EIST is controlled by Windows, and utilizes the different "power schemes" you may have seen in your control panel.

Great - so what does that mean for overclocking?

Many overclockers, both new and experienced, prefer to simply leave these settings disabled. Sometimes the constant adjusting of multipliers and voltages causes instability in their overclocks, other times they just prefer to see their components running as fast as possible all of the time. If you are among them in either case, then feel free to disable both C1E and EIST in the BIOS. Once you stabilize your overclock, and you find you'd like to enable one or both of the features, it's always a good idea to re-test your stability once they've been activated, just to make sure that they won't cause any problems.

Great idea for this thread.

When Overclocking it is usually suggested to Disable Intel's Speedstep, or C1E.
I have it Disabled 24/7

Same thing Goes for AMD's Cool n Quiet Technology. Disable it.

Whether or not you're able to keep SpeedStep enabled depends entirely on your board and how good its bios is. Intel has done a really nice job with their variant, so for obvious reasons, if you can keep it on, it's a good thing. AMD chipsets have always had problems with their variant, Cool N Quiet, with respect to overclocking and it's generally better to keep it off, which is unfortunate.

However, it's always good to keep in mind what it is you want the machine and your overclock to accomplish? If, for example, you can OC your cpu to 3.5GHz with SpeedStep and OC to 3.6GHz without SpeedStep, then you've got to weigh your decision. I would personally stay at 3.5GHz with rather than 3.6 without... mainly because at that point, that extra 100MHz isn't actually doing much for you other than giving your bragging rights; however, keeping SpeedStep enabled is doing something for you.

Should I have it enabled then? I'm only back down to 3.4

If your OC is stable with it enabled, then yes, enable it.

Great article, skunk, and great extra pointers, fumz. I have had this disabled for a while, now, but I saw benefit to having it enabled before - and I think it is going to get enabled again.

ya I might as well. . no need to be always runnin at 3.4

might as well only have it crank up when needed. although the system is probably a little more "Responsive" with it disabled right? or no not really.. such a small margin we Humans cant tell.

I enabled the Speedstep and disabled the C1E and CPU-Z never reported anything above the 6x multiplier, showing my speed at a very slow 2.4 GHz. I have now enabled both and am going to test to see - I have also bumped my OC up to 3.3 GHz and changed the RAM timings back to optimal and changed the voltages to auto to see what happens. Hopefully, now that I know a bit more about the timings as well as the linking versus unlinking of the FSB and RAM speeds, I'll be able to achieve a better, more stable OC - with the Speedstep enabled.

Nope - with both SpeedStep and C1E I have the same problem - CPU-Z never reports the CPU speed going above 6x multiplier.

#$%!#$%!#$%

what.. have you fried something. Maybe your CPU is dying.. sorry to say something soo bad. if so you can upgrade like you've wanted to. If thats teh case can I have your old one just for fun.

Try hitting the cmos reset.. then that will set everything up the default way.. then you will see it downclocking very low, then jumping back up to 2.4 GHz. try that. but then you'll need to readjust everything. so write it down

Not really, I've had it disabled and there really is zero difference, at least as far as I can tell. It steps up the instant you need any more power at all.

With electricity prices going up and up (at least here in MD) every little bit helps