Dell Precision M3800 Owner's Review

Thank you for this update.

What happens if you disable ProcHot without setting a multiplier? does the CPU speed vary according to workload or does it remain at 800MHz?

John

 

the multiplier was to a defaut of 62 so the cpu went up to max when I disabled prohot without enabling the multiplier. if I enable the multiplier the cpu stays at max but when I want to set a value the max I can put it 32. going under 32 lowers the cpu speed.

 

RMClock does not seem to work with the m3800 proc. it says unknown type or something.

 

Thank you. I'll try this on my E7440 with 45W PSU out of interest but expect I will have to use some intermediate CPU speed to get a balance between performance and heat / fan noise.

RMclock was last updated in 2008 to support the Core 2 CPUs. I used to use it for undervolting but haven't tried it with the latest Intel CPUs because Intel made it increasingly difficult for users to tweak the settings.

John

 

yes I noticed RMclock is old. I'll keep using throttlestop and see if I can get it to disable throttling without disabling ProcHot. I will also try disabling ProcHot, lowering cpu clock and monitoring the temps.

 

So first battery test: 3 hours and a half with BD ProcHot disabled => 2800-3000mhz. Wifi + one VM machine running. no intensive load for the moment. I will test with more VM machines running.
for additional details on 'BD' prochot please read here (throttlestop auther reply to my questions):
http://forum.notebookreview.com/hardware-components-aftermarket-upgrades/531329-throttlestop-guide-231.html

 

That's a useful clarification about the function of BD Prochot. Dell have evidently taken the easy route of using this to get the BIOS (if uncertain about the PSU capacity) to signal to the CPU to throttle itself. When I tried using an under-rated PSU on my E7440 I got the impression that the whole system bus speed was reduced. If this was the case then you may therefore find that disabling BD prochot but using a slow CPU speed gives you adequate performance with longer battery time.

Unfortunately, there's no similar workaround for the other problem in my case, that of charging the battery with what the computer considers to be an under-rated PSU.

John

 

the throttlestop author reply just in case:

Just to clear something up. The option that you toggled in ThrottleStop is called BD PROCHOT. It sounds the same but this is different than PROCHOT.

PROCHOT is the signal that goes off within the CPU when the CPU reaches the maximum safe operating temperature. When it reaches this temperature, the CPU will start to thermal throttle. It will slow down to 800 MHz and it will drop the core voltage which allows the CPU to cool down to protect itself from being damaged. It would not be a good idea to disable PROCHOT because doing this could permanently damage your CPU.

BD PROCHOT stands for bi-directional processor hot. This is a signal path to your CPU. Other sensors on your motherboard or GPU or your battery or Dell power adapter can send signals to your CPU using this method. These signals can trick the CPU. When BD PROCHOT is active, the CPU responds just the same as if it was too hot. It slows down to 800 MHz which significantly reduces power consumption and heat output.

My opinion is that some manufacturers are over using this method of CPU control. Running at 800 MHz is a very severe form of throttling. If a sensor goes bad, the CPU can end up permanently stuck at 800 MHz. I do not agree with this so that is why I included an option in ThrottleStop to disable the BD PROCHOT signal path. This prevents outside sources from forcing your CPU to throttle down to 800 MHz. Disabling BD PROCHOT does not interfere with your CPU from slowing down to 800 MHz. If your CPU gets too hot and starts overheating, it will slow down whether BD PROCHOT is checked or not.

Now back to your question. Your Dell M3800 is using the BD PROCHOT signal path. The ThrottleStop Set Multiplier feature will be ignored when a signal is being sent to your CPU using BD PROCHOT. The only way to control your CPU with Set Multiplier is to disable BD PROCHOT.

Is it 100% safe to disable BD PROCHOT? That is impossible to say. My best guess is that Dell designed this feature to protect your battery from being damaged. There are videos on YouTube showing laptop batteries and laptops going up in smoke. Reducing the speed of your CPU reduces power consumption and is a good way to prevent this from happening. Even if a battery does not catch on fire, drawing too much power out of a battery too quickly can shorten its life span. A battery might last for a few years if you only draw 10 Watts from it at any given time but if you draw 40 Watts out of the same battery on a regular basis, it might be dead in 3 months.

With all ThrottleStop features, you are on your own. If you think Dell is being way too conservative then disable BD PROCHOT and run your laptop at whatever speed you like. If you think that Dell probably knows what they are doing then leave BD PROCHOT enabled and suffer with an 800 MHz laptop when on battery power. I mostly use my laptop on AC power so I have not done any real world testing. Send me an M3800 and a box of batteries and I will see what I can figure out.

 

Hi all. Have a couple of questions. I bought an M3800 last night. 512gb ssd, 4702hq, 16gb ram, 3200x1800 screen.. 61Whr battery.

Wanted to know if there's space for an additional hard drive in this setup. I know 512gb ssd versions normally have 91Whr battery.. Which I thought at first was the reason you couldn't add another storage drive. Looking at some pics of the inside of the chassis yesterday though, it got me thinking that I can't add another drive even with the 61Whr / 512gb setup - can't see any available bays.

Could someone clarify? Thanks!

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One additional questions... There's two fans on the m3800. Are they intaking air in or blowing out of the bottom? I have a laptop cooling pad.. Zalman model that blows air into the bottom of the laptop. Wondering if I'm going to slow / disrupt the airflow if I use it with the m3800. Thanks

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