is my new motherboard defective?

[rob613]

I have a handful of fully working T42p systems and a few broken ones.
An associate helped me to diagnose a problem I was having on one of the working ones as a failing motherboard so I replaced it with a new one that came within a bottom case so all I had to do was a CPU chip swap, heat sink with fan, the display, and so forth. It all went very smoothly and the seller of the new motherboard also very helpful and knowledgable.

I think that the new motherboard might have a problem and I was wondering if what I am seeing is a known problem.

The primary symptom is that under Windows XP, under "my computer" properties, it shows the CPU speed at something like 500 Mhz or 170 Mhz. It does this even when task manager shows CPU load, and having tried to disable Speed Step in BIOS and also in the power settings.

Is that ever a symptom of a bad motherboard?

I've tried a few other parts changes and disk environment changes and still find that this symptom is tied to this motherboard regardless of which CPU chip I have installed.

This system is used regularly by my kid.

Among my non-working systems is an R50p and a T42p each with the symptom that the display goes black after a few seconds of proper brightness. Not totally black, a faint outline of open windows is visible. To temporarily clear it I press and release the lid close button. Or I can work around the problem by using an external analog monitor.

My kid's disk within either of these systems works and I see full CPU speed (1.79Ghz or 2.0Ghz) on the blanked-screen systems.

A minimal OS disk environment from one of those systems boots just fine in my kid's system with the new motherboard, but shows the same low CPU frequency symptom / problem.

Swapping the heat sink fan with the T42p system does not change this result. Swapping the CPU with the R50p system also does not change this result.

One other symptom I've noticed is that on first boot-up neither heat sink fan in the new motherboard spins up quite as loudly or to as high a speed as in other systems. Since that doesn't change with a heat sink (with fan) swap I think that too might be a symptom of this new motherboard.

Running PC Doctor diagnostics everything checks out.

Even swapping around some memory modules doesn't change the above symptoms however I did find one 1Gb module that has some memory pattern test failures when in one of the slots of the new motherboard. The symptoms remain with two such modules without any error.

Any advice as to whether this is a bad motherboard or possibly a whacky BIOS setting or version that can be corrected will be very much appreciated.

If only it would be that the system slowed down the CPU clock speed to the minimum necessary to keep things running I'd be very happy but my kid found this symptom only after seeing that system seemed awfully slow, and I verified that it doesn't come back to maximum CPU speed even with the CPU under load.

And all this running on AC power, by the way, through a good DC power supply. Same power supply was used on the dark screen systems.

[Neil]

Welcome to thinkpads.com! Seems like you're well advanced in working on ThinkPads for your first post here.

I'm curious what the first seven characters of the new motherboard's serial number are. That would tell us what machine it was designed for.

Also there is a setting in the BIOS>Config>Power > "CPU Power Management", that would normally be set to automatic. Maybe it's disabled. The setting enables or disables the power saving features that stops the microprocessor clock automatically when there are no system activities. Can't think of anything else that would cause low clock speed, unless it is just not the right board for the CPU's you are using.

As for the LCD going dark, that sounds most like a CCFL (lamp) going bad.

[rob613]

The new to me motherboard came in a bottom case with first 7 digits 2373-KXU.
My t42p that I am using to write this is 2374-HTU, and I think most all are either 2373 or 2374.

The default BIOS setting was all that speed step stuff fully enabled. After I saw the problem I put it to disabled, and also put it to "custom" and selected full speed today. Today it is stuck at 598Mhz.

Is this a known failure mode for motherboards that the CPU is never allowed to go to more than 30% of its speed?

Is there any test with a Linux System Rescue CD that would give more information?

...

As to the 2 dark display systems, wouldn't the LED light part be a steady problem, not not reliably turn on after a screen close and re-open event? I understood this to be a known motherboard problem with the digital video, and that was why the analog video remained fine.

I think I did try plugging another known good screen onto it and it still had the problem.

[rkawakami]

Is there a good battery installed in the system? My understanding is that the system can throttle down if run without a battery.

[rob613]

Decent batteries marked as 99% or 100% charged which work for at least an hour were in at all times.

The behavior you are reporting might indicate that IBM designers felt it possible to draw more than 72Watts when running the CPU at full speed, and require a battery to be in place in case it needs more?

[ajkula66]

The behavior you are reporting might indicate that IBM designers felt it possible to draw more than 72Watts when running the CPU at full speed, and require a battery to be in place in case it needs more?

Correct.

Plug the adapter in, with the battery inserted as well, open 25 firefox tabs and let us know how the CPU behaves.

[Neil]

I had some other ideas, but let's see how the battery things plays out first. Then we'll go from there.

[Cigarguy]

Symptoms describe above could be caused by overheating. It maybe throttle down to save itself. When swapping HSF, did you clean off old TIM and apply new? If yes, double check that everything is seated and connected properly. Download, install and run HWMonitor and report back on CPU core temps.

Battery/power problems as indicated above could also cause the problem.

[rob613]

The batteries are fine. Not brand new, of course, but fine.

Running the CPUID Hardware thermal monitor on both my primary laptop and my kid's laptop with the new motherboard, shows that both are running at about the same THMD temperature 65 - 66 degrees C on mine (150F) and 68 - 69 degrees for my kid's. Both are at their respective minima.

The batteries on each are near 100% charge and about 46% wear level. Actually my kid's battery is showing much better current capacity than mine.

It seems to me that the cooling fan is spinning a little faster on my busy system than on my kid's idle system, and that might also explain why mine is running cooler, closer to the minimum temperature and his is a few degrees hotter but less than the maximum.

If the system is throttling itself down due to overheating would this really start just seconds after booting up from hibernated state on a cold winter day? The CPU speed shows 598Mhz all day today even when just booted up fresh or from hibernate, and regardless of whether the system is busy or not.

And it doesn't appear to be the CPU chip itself since I changed that. I changed it with wiping off all heat sink compound before changing the heat sink and the cpu chip separately. The 1.8Ghz CPU was also running at 527Mhz, my kid's first complaint.

[rob613]

Good news!

I did a lot of benchmarking and was still seeing some strange systems. The CPU-Z tool showed me that the new motherboard had an older BIOS. I got to run a BIOS update and immediately after that I am seeing the CPU speed step / multiplier behave better. It still does seem to throttle down at times I don't think it should but it is now looking fairly reasonable.

I also think that the heat sink fan is not spinning up as fast as it should on power up and this might be contributing to the problem.

[RealBlackStuff]

I see you didn't answer the "new thermal paste"/TIM question.
If there's no paste, a laptop will heat up very quickly.
At a cold boot the fan only comes on for a few seconds and then stays off until heat has built up eventually.
The slower one (or maybe both) of you CPU-coolers may need cleaning and/or oiling of the fan itself.
See http://forum.thinkpads.com/viewtopic.php?f=2&t=112342