m6800 which power adapter does not throttle CPU?

Hi all,

I keep my m6800 always on the latest BIOS - currently A14.

That throttles my CPU down to 400 or 800 Mhz if I use a power adapter with 90w, 130w and 150w.

Does anybody know the smallest (small size and weight for travelling reasons) power adapter with enough watt which does not throttle the m6800 with BIOS A14?

I have the m6800 with i7 4800mq, GPU is AMD m6100.

Opened a Dell support case by e-mail about 6 weeks ago. Said to forward to correct department. Never heard back. Telephone support in a call center was a complete waste of time.

Some more background:

Not sure which BIOS I had initially (bought in Dec 2013). But 90w travelling adapter worked at full speed. Just charging was slow. Booting the laptop after a BIOS update told me to use 130w to get full functionality which worked until BIOS A08 if I remember correctly. Had to upgrade to that BIOS because of a keyboard problem which produced two or three letters on a single key press for some keys.

After that BIOS update the system said 180w, now it even says 240w as smallest power adapter.

If I use a smaller one (tested 130w and 150w) the CPU throttles down to 0,39 or 0,79 Ghz - seems to depend on fresh reboot or suspend/resume how low it goes.

I can disable SpeedStep to get full CPU speed all the time but that gets my battery time down from ~4h to ~2h at moderate usage when not plugged in. Switching that BIOS setting when plugging in the power adapter is at least one hibernate/resume cycle which I find inconvenient.

Thanks for any help - if the BIOS throttling can be disabled that would be welcome as well ;-)

Thanks
Sven

 

it is kind of a software throttle if similar to the older gen.
try throttlestop(works for my m6600) or intel XTU(in addition, for m6800, you can use xtu to unlock a few multiplier in normal use)

otherwise a 210W(which is larger than a 240W) is minimum in order to prevent the throttle.

 

Hi baii,

I use ThrottleStop but it is not dynamic, so I always have to change profiles manually to get different clock speeds. Inconvenient if you have got used to SpeedStep doing that for you ;-)

Do you know if the throttling params can be adjusted to get them back to the way older BIOS versions were configured?

Did you test with 180W? Does that throttle as well?

I just use the m6800 for software development with no need for an explicit GPU, just enough RAM, CPU and storage to drive a few virtual machine test servers on my laptop. So the power consumption was never a problem with a 130W power adapter with older BIOS versions - sigh...

Thanks
Sven

 

Use ThrottleStop to disable the BD PROCHOT feature. This should allow you to use a lower rated power adapter without your CPU being locked to 798 MHz. Disabling BD PROCHOT prevents the power adapter from telling your CPU its power rating. This will put you in control of the situation.

If software is reporting that your CPU is running at 0.39 GHz then it is wrong so ignore it. Can you post a screenshot of that?. Most Intel mobile CPUs run at a base clock speed of 99.77 MHz and then they use a multiplier of 8 so the minimum possible speed is about 798 MHz (99.77 MHz X 8). The WIndows Task Manager is a work in progress and I have seen it report MHz numbers that are simply not true.

If you are using ThrottleStop, do not disable SpeedStep. Use the latest version from my signature. I do not recommend using Intel XTU while running on battery power. It is an inefficient program that interferes with the percentage of time a CPU can spend in the low power C States. Maximizing the percentage of time that your CPU spends in one of the low power C States is the best way to minimize power consumption which will maximize run time while on battery power.

@SvenC - Post some ThrottleStop screenshots if you need some help. When SpeedStep is enabled, your CPU speed will be completely dynamic.

 

Hi unclewebb,

setting only bd prochot works. But it seems that the CPU does not fall below 2,6 Ghz any more, even with balanced power plan. With the 240w adapter I get 0,8 to 1,4 Ghz for an idle or little used system.

Can that bd prochot setting be persisted so that rebooting works at higher speeds as well? Tryed with ThrottleStop 6.0: bd prochot seems to be kept while my machine runs even with TS closed but rebooting the machine gets it down to 0,3x Ghz until I start TS.

Even if 0,3x is reported wrong (see my task manager of Windows 10 rtm) and ~800mhz would be correct the system is suuuper slow. Opening any application takes forever. E.g. Windows Explorer takes 5 seconds to start and you can see how individual visual elements like folder hierarchy and disk drives are drawn.

Any chance to get battery charging to work with lower wattage as well?

Thank you very much for that hint!

 

Tried battery charging with 150w adapter with ThrottleStop running with that bd prochot setting. Did not help to get charging work at a normal rate:

Left the laptop alone for about an hour and got the battery from 38% to 39%.

240w would not take much longer than 1 to 2h to get it fully charged when the laptop is used.

 

Here is my experience on m6600:
to "un-throttle" I literally just need to turn on throttlestop with its set multiplier set to certain multiplier w.o touching any other option. bd prochot etc is not needed.

It literally wont charge when it is turn on, hardware limitation, no way around it.
I believe putting it in sleep or turn on will make low wattage charger charge it properly.

Just saw your setting, keep eist(speedstep) c1e checked and tick set multiplier.
Sorry I didnt explain how I set it up in first place.

I had no problem running CPU full powered with a 120W charger, but if I run the gpu hard at the same time, it will trip the charger protection and it get a instant shut off.

 

SpeedStep needs to be enabled for ThrottleStop to work correctly. Your screenshot shows that you still have SpeedStep disabled and BD PROCHOT should not be checked.

ThrottleStop 6.00 was a good program but ThrottleStop 8.00 is better. The new version will give you a lot more control over your Core i7-4800MQ.

As I mentioned, 0.3 GHz is a speed that is physically impossible for a Core i7-4800MQ to run at. When the Task Manager shows a number like that, it might be a sign that your laptop is using clock modulation throttling. You can use ThrottleStop to fix that problem.

In the Options window, there is a feature called AC On - Battery Off. This allows ThrottleStop to control your CPU when your laptop is plugged in but ThrottleStop will sit back and let Windows manage your CPU when you switch to battery power. I never use this feature but maybe this option is for you.

On 4th Gen CPUs, the reported MHz is not a good way to judge power consumption. Cores should be spending 99% of their time in the low power C7 state. In this state, 800 MHz or 3000 MHz makes no measurable difference to power consumption because the cores are spending most of their time disconnected from the voltage rail.

I found a bug in Windows 10 that was putting a significant and continuous load on my CPU. If tasks like this are left running in the background, they will kill battery run time. If your cores are not spending 99% of the time in C7 when you are idle at the desktop then find the tasks that are keeping your CPU busy and get rid of them. When idle, the C State data in ThrottleStop is more important than MHz.

 

Thanks baii and unclewebb,

I'll keep an eye on the options. Great tool and great skills to dig that deep into drivers and HW!

I guess my option would be "AC On - Battery Off IF charger has less than 210W" ;-)

I found no obvious process at idle times with constant CPU usage. System interrupts is between 0 and 2%. A little chrome, dwm, outlook and taskmgr or procexp if I look for busy processes.

But of course if I start VMs and some Visual Studios battery time goes down.

Thanks again
Sven