Weird liquid damage symptom-CPU downclocking to 100Mhz

[imrazor]

I have an older laptop, a Dell Precision M6600 that took a hit from 500ml of Diet Coke. After letting it dry out for quite a while, I was surprised to find that it actually booted. (The keyboard was also dead, but in the meantime I'm just using a USB keyboard.) But it's occasionally displaying a weird symptom. Sometimes the CPU will downclock to ridiculously slow speeds - like 100 MHz.

I've managed to counteract this by disabling C-States and SpeedStep in the BIOS, though this has the unfortunate side effect of meaning top speed is 2.4GHz instead of 3.0 GHz, as it won't TurboBoost any more. Any other suggestions for fixing this, other than sending it to a liquid damage specialist? It's not worth that much.

For the sake of science and posterity, any theories on what might be causing it to downclock so low? Lack of voltage? Deluged sensor?

 

[luckymatt42]

Once liquid enters into the equation...it could be literally anything. All it takes is for the right capacitor or other surface mount component to short out, and figuring out which one it is would be a nightmare.

I guess your question is there any "standard" procedure that would pinpoint the problem, and unfortunately no. Good news is there are some great laptops out there these days in any and every price point and configuration you can imagine.

 

[shmoochie]

Gah, I have no idea how you would troubleshoot that water damage without testing each part. If you have a multimeter, you could tests the voltages coming out of the charger and mobo to make sure they are stable.

One thing you could try would be setting the minimum power state to something higher than 5% and then renabling speedstep and c-states.

 

[imrazor]

It just seems a shame to chuck it in a landfill when its still reasonably capable. As part of my post-liquid testing, I installed a game (Deus Ex:Mankind Divided) and it was running at 35 - 45 fps on medium-high settings.

I do have another CPU I could put in, but I'm suspecting that this is motherboard damage, not a CPU problem.

 

[dudio]

What are some off the system temperatures when the CPU throttles down? You can use HWInfo (free) to see that.
If youre comfortable with it, you should open up the laptop as much as possible and clean with 90% isopropyl alcohol

 

[imrazor]

@dudio Disassembly on this laptop (like most notebooks) is a nightmare, and I don't really have a good workspace for a complete teardown. I can do minor repairs (e.g., replacing the hard drive) with the space and tools I have available.

I'll try and find a good temperature monitor to check temps (any thoughts on Speedfan?) The thing is it does its insane throttling when it's under nearly zero load, so I don't think it's a cooling issue.

 

[dudio]

I recommended HWInfo because it seems to be quite reliable. Soda/pop doesn't evaporate well because it's a syrup based nightmare, and likely conductive for quite awhile. Determining if it's temperature causing the throttling may help pinpoint where the fault is...insane voltages to CPU from a short?..Fan not turning or dead?..etc.
Cleaning is still highly recommended