CPU Throttling, CMOS Patch? (Inspiron 5150)

Question

I see under BIOS upgrades that there is a CMOS patch intended to cure bad CPU performance. It "Corrects Inspiron 5150 systems that experience slow performance when running CPU intensive programs after a motherboard replacment." I have not replaced the motherboard, but I have upgraded the BIOS of my Inspiron 5150 from A26 to A37, and I *do* have bad performance when running CPU intensive programs.

The actual problem is that the CPU quickly reaches 70-75 degrees C and start throttling. It typically goes to T2 (25% throttling), but quite often all the way to T6 (75% throttling). Will this patch help me, or do I risk to damage the system by applying an irrelevant patch?

I run both Linux and Windows XP, but I mainly run CPU intensive stuff under Linux, and anyway don't know how to monitor this kind of stuff under Windows, so I do not know if it is sensitive to the operating system.

/Jakob

NemesisDB · Answer

i hope dell's to the point where the patch won't run if it's not needed... that said, your problem is heat related and the patch likely won't help

do three things: 1) downflash to a bios before those "thermal dust" enhancements (35 i think?)

2) buy a can of compressed air, turn the computer off, shoot air into the back exhaust vent (not the bottom intake vent). do this bi-weekly. if there is a lot of dust accumulation and this doesn't help you may need to manually clean the heatsink, or have it replaced if still under warranty

3) download fanGUI and force your fans on high sooner

schiotz · Answer

Thank your for your reply, I will try it out, but I am afraid that buying one of the first machines with a 3.05 GHz CPU maybe has a price .....

By the way, what it this thermal dust enhancement? I cannot even begin to guess what "thermal dust" could be.

/Jakob

NemesisDB · Answer

machines with the form factor yours has (in particular 5100s and 5150s) have more issues than normal with dust/heat.  The intake vent on the bottom s*ucks in air and runs it over a heatsink and out the back exhaust vent.  Often, dust is pulled off your desk, lap, or other surface and some of this is deposited on the heat sink.  The dust acts as insulation, preventing the heat sink from transfering heat the the air and causing overheating problems.  As accumulation increases, the CPU will begin throttling itself sooner, fans will run faster and more often (tanking battery life), and, in the extreme, the computer will auto-shutdown to protect itself.   The traditional solution to this has been to buy a can of compressed air, turn the computer off, and shoot it into the back exhaust vent (not the bottom intake vent) in the hopes of removing dust -- most people recommend doing this every couple of weeks to prevent accumulation.  If you already have accumulation though, air may not be enough -- and a manual cleaning or a new heatsink assembly (if your under warranty) may be in order.   The most recent couple of bioses claim to fix this dust problem.  In actuality, they simply run the fans much less often (and in turn cause much higher idle CPU temperatures) in order to draw less dust in.  Personally, I think running the fans less is not the ideal solution.  As long as you clean/air blast the heatsink occassionally, I would not recommend these bioses.

schiotz · Answer

Thank you VERY much indeed! Not only for the detailed explanation, but for the excellent advice. I blew air into the machine, and visible amounts of dust came out - it seems to be an excellent desktop vacuum cleaner :-)

The operating temperature while compiling dropped from 70-75 deg C to 59 deg C, and no more throttling. Great!

Next step is downgrading the BIOS and/or getting the i8kutils (fan control to Linux) to work.

Thanks again!

Jakob

NemesisDB · Answer

yup ... and if throttling still happens (or if you think those temps are high) ... and if your under warranty, get a new heatsink ...   there's probably a decent amount of caked on dust that air won't remove

fredthomke · Answer

Yep, I, too, had upgraded to A37 BIOS, only to find my computer would overheat and LOCK UP!! After lots of downgrade/upgrade of the different BIOS versions (A32 through A37), I found that the A36 and A37 would not let my fan run fast enough, causing the overheating. As soon as I downgraded to A35, all seems well.

It had gotten to the point where I could only run for an hour or so, then the system would lockup, forcing me to hard-shutdown then restart. With A35, I can run for DAYS with no heat problems.

Fred Thomke

schiotz · Answer

I have stayed with the A37 BIOS. It will let the fan run at full speed if needed, it certainly did that when the cooling plate was full of dust, but after I blew out the dust it has worked fine. Even when it has been compiling C++ code for two hours straight (with two compilers running simultaneously) it only reaches 61 degree. I don't think that is excessive, it is comparable to other machines I have seen.

But blowing out the dust seems to be important. I plan to do it every second week.

/Jakob

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CPU Throttling, CMOS Patch? (Inspiron 5150)

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