Fan will not go to full speed on ProBook 4720s

[fanerror]

to: erhart-jir

there is a temporary workaround. do it only at YOUR OWN RISK.

this procedure only works on ProBook 4720s F.20 bios. DO NOT ATTEMPT THIS METHOD ON OTHER MODELS!!!

it works only when the laptop is on AC POWER. download "read and write utility" from http://rweverything.phpnet.us/. run the program then click the EC icon (embedded controller). in the embedded controller window that opens you will see a matrix of 16x16=256 numbers choose the one in column marked "05" and row "D0". that number has an offset address of 213(in dec) and probably a value of 1E.

(if you didn't find it don't attempt to change a random number, its risky)

change the value to something from 0 to 70 (don't go over 7F) and the fan will speed up to the desired value.

also do not change any other values - risk of hardware damage

the procedure must be repeated on every startup

this procedure only works on ProBook 4720s F.20 bios. on other models the offset is different so do not attempt this method !!!

do it at your own risk only

the core of the problem probably lies in the bad DSDT table (that came with the bios), but i guess you would need an expert to fix it.

if you need more help you can leave a post

[erhart-jiri]

to: fanerror

Thank you for your reply, it isn't the type of solution I was wondering to receive, but at least I know where to search further and I can use the computer without having to worry about the temperatures.

If anyone knew a way, how to solve this problem OS independently, like somehow fixing the current BIOS, please post it here. I'm sure it would help more people than just me.

[barbahann]

Fanerror:

Your solution changing the 05 D0 value works peaty well when the laptop is connected to the AC power, do you have the address when the laptop is in battery mode?

Do you know a permaneth method?

[fanerror]

to: barbahann:

A not so elegant solution would be to change and keep changing the value at 06 D0 (right next to 05 D0). Something keeps writing into this adress, so you would have to write in it faster (~every second). You can use the command window in RW to wtire a simple script that does just that.

in the command window you can use this script line to write the value of 0x50 on every 1000ms ( = 1 second)

LOOP{0, DELAY 1000; wec 214 0x50}

this solution doesnt work very well and the fan's speed will wary a bit.

the only permanent solution is for someone to fix the bios. (or maybe the problem lies in the ACPI tables)

[gkol]

Same problem for me. Still no solution?

[Kyle_W]

Your notebook is an Enterprise/Business model. I would recommend posting this in the HP Enterprise Support Forums for better coverage.

You can access the enterprise support forums at the following link.

http://h30499.www3.hp.com/

[adv74]

I sent the laptop to the service for repair. Final report of the repair service: faulty mainboard
However, I'm 100% sure that the defect was caused the BIOS update...
HP notebook never again!

[AxshunJaxun]

Hello all, 

I saw a very similar issue on this thread  The user had a BIOS update go through and began noticing that the fan didn't seem to be running, so naturally it was believed to be associated with the BIOS update. After much troubleshooting, reinstalling and trying to rollback the BIOS, the user decided to visually inspect the fan as a last resort. It turned out that there was a lot of dust preventing the fan from operating at its full capacity. He cleaned it and it immediately began to run properly.

More dust accumulates quicker than one might think. Even if you think the environment is not particularly dusty, it is.

If a computer is 1+ year old and it has never been cleaned, it is much more likely that dust is causing heat and/or fan issues than it would be for software updates to cause an issue like this. Not saying it is impossible but it's just a lot more likely for it to be due to dust buildup. 

It is always better, though it is tedious work on some units, to open the notebook up and use canned air to blow dust out of the computer rather than blowing from outside the vents into the computer. Blowing from the outside-in, blows those dustbunnies further into the computer where there is less circulation and parts are more susceptible to dust and the effects of heat.

See the pictures below

One year of buildup in a regular non-smoking home

Before being cleaned

After