- Joined
- Oct 14, 2007
"My CPU Isn't Running Its Rated Speed!" / "My Multi is Stuck at 6x!" / etc.
This question gets asked so frequently, I figured it merited an easily searchable post. So I'll post the explanation. If anyone who has ever seen it asked would be so kind as to reply with any phrase you can think of that might be used to ask this question to make the thread easily searchable, it would be greatly appreciated. Tags may be helpful as well. Thanks everybody!
So, you get a new computer and your CPU is running what you percieve with monitoring software to be too slow. What's going on? Most likely EIST (Enhanced Intel Speedstep Technology) or C1E (Extended Halt State) are enabled in your BIOS.
We'll start with EIST. Here is Intel's explanation:
Per this data sheet, Intel describes C1E as follows:
To keep your CPU from doing this, search for things in your BIOS labeled EIST / Enhanced Intel Speedstep Technology / Speedstep and C1E / Halt State / Enhanced Halt State; basically anything having to do with those terms. Disable them and your CPU will run full speed all the time.
Should you do this? It's up to you. Some people say it affects stability at high overclocks. Unless you're really pushing the envelope it's usually not a problem. If you're going for max clocks, they should be turned off anyway. The problem is the voltage drop, even at 6x, may be too much for your CPU and the system could become unstable. Likewise, if you want to change the multiplier from anything but default, you must disable these features or you could run into problems (i.e. I've seen some even have to reflash their BIOS because of that, though it's rare).
Aside from those scenarios, it doesn't really hurt anything. The change is instantaneous and no human could ever tell when it happens. See for yourself; pull up CPUz and then run Prime95 or whatever you'd like to use to put your CPU under a load. Watch the change. From when the program loads the CPU to when the multi changes is imperceptible. Put succinctly, if you're not benchmarking or under either of the two scenarios above, you need not worry about it.
This question gets asked so frequently, I figured it merited an easily searchable post. So I'll post the explanation. If anyone who has ever seen it asked would be so kind as to reply with any phrase you can think of that might be used to ask this question to make the thread easily searchable, it would be greatly appreciated. Tags may be helpful as well. Thanks everybody!
So, you get a new computer and your CPU is running what you percieve with monitoring software to be too slow. What's going on? Most likely EIST (Enhanced Intel Speedstep Technology) or C1E (Extended Halt State) are enabled in your BIOS.
We'll start with EIST. Here is Intel's explanation:
All C2D / C2Q chips down clock by reducing the multiplier to 6x and dropping the Vcore. i5 / i7 chips work in a similar fashion, but I haven't looked to see what the normal downclocked multi is. The principle is the same.Enhanced Intel SpeedStep Technology allows the system to dynamically adjust processor voltage and core frequency, which can result in decreased average power consumption and decreased average heat production. By decreasing power and heat on desktop PCs, system builders can (depending on system configurations) potentially lower acoustics, and even develop more innovative small form factor designs. Additionally, this feature can help address power concerns in companies with sites approaching the limits of bounded electrical infrastructures. Combined with existing power saving features, Enhanced Intel SpeedStep Technology can provide an excellent balance between providing power when you need it and conserving it when you don’t.
Per this data sheet, Intel describes C1E as follows:
So, basically they are two things that make the CPU perform very similar actions.Extended HALT state is a low power state entered when the processor core has executed the HALT or MWAIT instructions and Extended HALT state has been enabled via the BIOS. When the processor core executes the HALT instruction, the core is halted. The Extended HALT state is a lower power state than the HALT state or Stop Grant state.
Note: The Extended HALT (C1E) state must be enabled for the processor to remain within its specifications.
The Extended HALT state requires support for dynamic VID transitions in the platform. The processor automatically transitions to a lower core frequency and voltage operating point before entering the Extended HALT state. Note that the processor FSB frequencyis not altered; only the internal core frequency is changed. When entering the low power state, the processor first switches to the lower bus to core frequency ratio and then transition to the lower voltage (VID).
While in the Extended HALT(C1E) state, the processor processes bus snoops. The processor exits the Extended HALT state when a break event occurs. When the processor exits the Extended HALT state, it first transitions the VID to the original value and then changes the bus to core frequency ratio back to the original value.
To keep your CPU from doing this, search for things in your BIOS labeled EIST / Enhanced Intel Speedstep Technology / Speedstep and C1E / Halt State / Enhanced Halt State; basically anything having to do with those terms. Disable them and your CPU will run full speed all the time.
Should you do this? It's up to you. Some people say it affects stability at high overclocks. Unless you're really pushing the envelope it's usually not a problem. If you're going for max clocks, they should be turned off anyway. The problem is the voltage drop, even at 6x, may be too much for your CPU and the system could become unstable. Likewise, if you want to change the multiplier from anything but default, you must disable these features or you could run into problems (i.e. I've seen some even have to reflash their BIOS because of that, though it's rare).
Aside from those scenarios, it doesn't really hurt anything. The change is instantaneous and no human could ever tell when it happens. See for yourself; pull up CPUz and then run Prime95 or whatever you'd like to use to put your CPU under a load. Watch the change. From when the program loads the CPU to when the multi changes is imperceptible. Put succinctly, if you're not benchmarking or under either of the two scenarios above, you need not worry about it.
Last edited: