cpu fan

HI everyone.

I am new to the forum, my pc problem brings me here......

My brand new PC (HP slimline) runs really well, the only problem is the annoying constant fan noise. (CPU fan)

As I have downloaded Autocad on to my pc and do not really want to exchange the unit (I've set it up/installed everything I want on it) I have bought a replacement fan, the same size.

When the new fan is fitted it runs fine and much quieter than the original, but as soon as the pc is turned on it states 'cpu failure, computer will shut down' (something like that) and immediately shuts down automatically.

I managed to run the bios mode once to check the settings but my bios menu looks nothing like the example given on the HP help website:

http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&docname=c00013522

I have since reconnected the old fan and all is well but still noisey!


So, my question is....... what do i need do to get this new fan working? The fan works fine, the problem is the pc thinks it is not working.

Many thanks


Russ

russ_1380 said:

HI everyone.

I am new to the forum, my pc problem brings me here......

My brand new PC (HP slimline) runs really well, the only problem is the annoying constant fan noise. (CPU fan)

As I have downloaded Autocad on to my pc and do not really want to exchange the unit (I've set it up/installed everything I want on it) I have bought a replacement fan, the same size.

When the new fan is fitted it runs fine and much quieter than the original, but as soon as the pc is turned on it states 'cpu failure, computer will shut down' (something like that) and immediately shuts down automatically.

I managed to run the bios mode once to check the settings but my bios menu looks nothing like the example given on the HP help website:

http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&docname=c00013522

I have since reconnected the old fan and all is well but still noisey!


So, my question is....... what do i need do to get this new fan working? The fan works fine, the problem is the pc thinks it is not working.

Many thanks


Russ

Click to expand...

Did you remember to put thermal paste on the CPU when connecting the new fan?? Thats what the problems sounds like to me.... without the thermal paste the CPU will just overheat pretty much instantly. Make sure to wipe the CPU completely clear of thermal paste with a paper towel and reapply about a bb sized amount. (if you have thermal paste, its only like 5 bucks if you don't) And also what do you mean here "When the new fan is fitted it runs fine and much quieter than the original, but as soon as the pc is turned on it states 'cpu failure, computer will shut down' (something like that) and immediately shuts down automatically." Did the fan work at all?? I'm not trying to be a troll these are just common questions.

Hope it helped,
Brick

P.S. Did you buy the fan online?? If so can you post a link to it??

How many pins on the original and new fan?

HI

Yeah no worries.

I didn't make it clear in my first post sorry; I have not replaced the the heat sink, just the fan so I doubt the paste will be the prob as its never been displaced.

My original fan works fine but is noisey, hence why I want to change the fan.

The new fan works fine (i.e spins nice and quietly, far better than the original fan) when the power is turned on. The error message appears on screen about 5-10 seconds after the machine is turned on (booting? - I don't know the terminology sorry).

So.....the problem is not the fan, but its as if the computer merely 'thinks' the new fan i s not working correctly.

Does that make sense?

I have checked the voltage on both the new and old fans, both 12v.

Both fans are the same size and have same number of fins

I'm confused

If I said I knew what the problem is, I'd be lying....... Try buying a fan+heatsink??........ Sorry man I'm really clueless on this one hopefully someone else can help.

Brick

cheers

Just seen my friend who is clued up on these things, he doesn't know either.

The new fan and old fan worked on his pc.

What we did notice is that my original fan is the hydraulic bearing type (AVC Asia Vital Components) and my new fan is ball bearing type.

My friend seemed to think it may be something to do with resistance differences between the 2 fans???

Anyone?

I could do with some advice

oscaryu1 said:

How many pins on the original and new fan?

Click to expand...

russ_1380 said:

Both fans are the same size and have same number of fins

Click to expand...

Not fins, pins. How many pins on the connector that you plugged the fan into. CPU fans are usually 4-pins with the fourth wire for PWM function that controls the speed of the fan in relation to the temperature of the CPU. If you plugged a 3-pin fan into a 4 pin connector, it's possible the BIOS would sense the absence of the PWM circuit and conclude that the fan has malfunctioned and go into self-protect mode.

jevery said:

Not fins, pins. How many pins on the connector that you plugged the fan into. CPU fans are usually 4-pins with the fourth wire for PWM function that controls the speed of the fan in relation to the temperature of the CPU. If you plugged a 3-pin fan into a 4 pin connector, it's possible the BIOS would sense the absence of the PWM circuit and conclude that the fan has malfunctioned and go into self-protect mode.

Click to expand...

^Ditto. On my ASUS motherboard, it just tells me that the CPU fan is absent, but on your HP it probably thinks that the fan is broken.

Ah my fault sorry guys......It is a 3 pin connector. Both new ad old fan are 3 pin connectors.

I think I have just found the problem........ I looked at the manufacturers spec of the original fan (4500rpm), and the replacement fan (1500rpm)

I did not realise this to begin with.

As my replacement fan spins slower than the original one, do you think this is causing the problem? i.e. the slower speed makes the computer think 'hang on, somethings not right here, i better say the fan is kaput'.

Would this difference in fan RPM be causing the problem?

Thanks

Russ

As one of the three wires is to relay fan speed signal, I suppose it's possible that the BIOS monitors fan RPM and is shutting down due to low RPM. What model Slimline is it? I'll try to find info on the main board.

That would be very helpful, thank you.

HP Pavillion Slimline s5300UK

Also when I get in to BIOS there is nothing I can see that will let me change anything to do with the cpu; speed, temp, diameter etc etc.

It appears that your MB is a Pegatron M2N68-LA, which since it is a proprietary HP product, no MB manual is available. ASUS support has manuals for different variations of the basic M2N68, but not for the LA variation, and all the others have 4 pin CPU fan headers - So, no specification or explanation of requirements for the CPU fan. If you Google "Pegatron M2N68-LA CPU fan," you'll find that you're not the only one to have had this problem.

Great stuff Jeverey, thank you.

I did some research as you suggested. In layman's terms (as I do not understand the proper terms), this is what I think is now happening:

BIOS (or some start up system) checks the fan speed....

....if the pre programmed 'minimum' fan speed is not reached, the computer thinks there is a problem with the CPU.....

......hence, throws the error message and shuts down automatically.

I believe this is happening as the new fan spins much slower than the original.

Now, to fix the problem I was thinking if I could get in to BIOS and somehow change this 'minimum' fan speed that the fan must reach in order to function correctly, the problem would be solved. Does this make sense? I'm a complete beginner at all this so apologies if its all wrong.

If my above theory is correct, the next problem is my BIOS has no CPU fan speed settings. Can I effectively add this feature on to my existing BIOS? If so how?

Many thanks, I think we are getting closer to solving the probs

Russ

russ_1380 said:

I did some research as you suggested. In layman's terms (as I do not understand the proper terms), this is what I think is now happening:
BIOS (or some start up system) checks the fan speed....
....if the pre programmed 'minimum' fan speed is not reached, the computer thinks there is a problem with the CPU
......hence, throws the error message and shuts down automatically.
I believe this is happening as the new fan spins much slower than the original.

Click to expand...

My best guess as well.

russ_1380 said:

Now, to fix the problem I was thinking if I could get in to BIOS and somehow change this 'minimum' fan speed that the fan must reach in order to function correctly, the problem would be solved. Does this make sense? I'm a complete beginner at all this so apologies if its all wrong.
If my above theory is correct, the next problem is my BIOS has no CPU fan speed settings. Can I effectively add this feature on to my existing BIOS? If so how?

Click to expand...

No you can't modify the BIOS yourself. You can update the BIOS with a newer version, but it does not appear that HP has any BIOS updates available. Even if they did it would not include that feature as HP apparently does not intend for the end user to modify the CPU fan.

I'd say your best bets are,

1. Call HP support - Maybe they can verify what we think is happening and offer a solution.
2. Buy a cheap higher RPM but lower dBA fan and give it a try.

jevery said:

2. Buy a cheap higher RPM but lower dBA fan and give it a try.

Click to expand...

^That's probably your best bet. What size is the fan (in mm)?