CPU Cooling Fan (Newbie Question!)

[Mist]

I have a variable speed fan sitting on the heatsink above my CPU,(1.3 Tualatin Celeron) and the fan speed is reported at 2556 rpm.

However, the fan is officially rated at 4800 rpm, which to me means that the faster the fan rotates, the cooler things should be.

So, my question is very simple, but I've been unable to find reference to this anywhere so far.

If I connected the fan directly to the PSU instead of it being connected to my motherboard, would that mean that the fan would run at a steady, non variable 4800rpm, since it won't be controlled by the motherboard?

I'm not bothered about the increase in noise level at the moment, I can sort that later.

I hope someone at this forum can give me the answer to this!!

Michael.

 

[godmare]

No, the motherboard only supplies power, not the speed adjustments to the fan.
Is the speed controlled by a rheostat/potentiometer (knob), or does it automatically adjust per processor temperature?

 

[Mist]

Thanks for replying so quickly.

No, there is no knobs or external methods of regulating the speed of the fan, so I would say that it's determined by CPU temperature.

So, since it's a new fan, I don't want to go ahead and wire it up to a PSU connector unless I know that it'll run constantly at the specified speed of 4800 rpms.

Michael.

 

[godmare]

Right, connecting it to the 4-pin psu connector wouldn't change anything. There's probably a jumper or some such thing on the fan that you can change to make it run full. Do you know what fan it is?

 

[Mist]

Listen, I really appreciate the time that you're taking to discuss this with me, you're the only person to do so after I've joined so many forums!!

Anyway, as to the HSF, it's a Cooler Master DP5-6J31C-0L and the actual fan itself reads on the top side: Silence CM 12V

On the underside it reads: A6025-25RB-3AN-P1 RIFLE. I checked, there are no jumpers or controls on the fan at all.

Interestingly, it mentions the wiring as Red = Pos, Black = Neg. No mention of the yellow wire at all and yet the yellow wire is connected to the MB as normal.

I say interesting because on a PSU, the red wire is rated at 5 volts and the yellow wire is rated at 12 volts and the black is the ground, so I'm asking myself why is there a yellow wire on the fan if it's not needed!

Michael.

 

[godmare]

You're welcome
There doesn't seem to be an abundance of information on this product.. are you sure it's supposed to be variable?
Are there any other wires running off of the fan (unscrew tha fan from the heatsink if it will help you see better)? We want to lookl for a thermistor running from the fan to either the heatsink itself, to between the processor and the heatsink, or possibly underneath the processor, into the socket.

One thing you can try real quick, too, is plugging it into your power supply directly. there won't be rpm monitoring like that, but you'll notice if the fan is running 2000rpm faster.

Also, are you using monitoring software to report the fan speed, or is that from the BIOS? If the former, check it against the BIOS reading at bootup.

 

[Mist]

Well Godmare, this is a link to the fan in question, the only difference is that mine doesn't have the copper at the bottom.

http://www.coolermaster.com/products/cpucooler/fcpga/cp5-6j31c-a4.html

I'm only assuming that it's variable due to the system software which obviously shows changes in the fan speed.

As I say, there are only three wires from the fan, the red, the black and the yellow and the yellow isn't even accounted for on the fan lable on the underside.

Michael.

 

[OulOat]

Originally posted by: Mist
Listen, I really appreciate the time that you're taking to discuss this with me, you're the only person to do so after I've joined so many forums!!

Anyway, as to the HSF, it's a Cooler Master DP5-6J31C-0L and the actual fan itself reads on the top side: Silence CM 12V

On the underside it reads: A6025-25RB-3AN-P1 RIFLE. I checked, there are no jumpers or controls on the fan at all.

Interestingly, it mentions the wiring as Red = Pos, Black = Neg. No mention of the yellow wire at all and yet the yellow wire is connected to the MB as normal.

I say interesting because on a PSU, the red wire is rated at 5 volts and the yellow wire is rated at 12 volts and the black is the ground, so I'm asking myself why is there a yellow wire on the fan if it's not needed!

Michael.

Don't mix up the wires from the fan with the wires from the PSU. Yellow wire from the fan is usually what the mobo usually uses to read the speed of the fan. By all means, try plugging it in the PSU rails, but you will need an adapter first if you don't have one already. The fan's rpms can be determined by two things, either your mobo or an internal temp diode. So hope it's your mobo because then it will turn faster once you switch to the PSU. Btw, why are you trying to override the automatic rpm adjustment?

 

[godmare]

Originally posted by: Mist
Well Godmare, this is a link to the fan in question, the only difference is that mine doesn't have the copper at the bottom.

http://www.coolermaster.com/products/cpucooler/fcpga/cp5-6j31c-a4.html

I'm only assuming that it's variable due to the system software which obviously shows changes in the fan speed.

As I say, there are only three wires from the fan, the red, the black and the yellow and the yellow isn't even accounted for on the fan lable on the underside.

Michael.

Hmmm, interesting. It doesn't say anywhere there about it being variable, either.

Originally posted by: OulOat
By all means, try plugging it in the PSU rails, but you will need an adapter first if you don't have one already.

Yes, of course, an adapter. If you have one, try plugging it to the psu.. if not, consider this over the standard 3- to 4-pin adapter.

Also, what does it say is the fan rpm in the BIOS bootup screen? If it says it's lower, than at this point I'm wondering if you're not having a motherboard or power supply issue, as far as the fan receiveing proper and regulated voltage.

 

[Mist]

Hi, thanks for joining in.

That makes sense about the fan wires, that's what I suspected too. So, if I remember to connect the red fan wire to the yellow PSU wire, then I'll get a 12 volt supply to the fan and it should run at 4800rpm.

As to why I want to change it, here's the story:

I was running an AMD K6-2 with the same stuff that you see in my signature, but it was becoming a bit too slow for the stuff I wanted to do, such as video and things. Also, it was keeping up with the Jones' syndrome too!

So, I didn't have a lot of money and at Xmas, I received gift vouchers for the local PC Superstore.

I realised that if I went for the P4 option, it would mean a new CPU, new MB and new DDR memory at the least, so a good choice was to cannibalise the stuff from the AMD system that I was using.

I knew that the Tualatin Celeron was basically a P3 and I could get that and a new MB for the gift vouchers plus a little extra cash, so I got a 1.3 Celeron and 370 board, took the stuff from my old system and put it in my new(ish) one. I also knew that I could overclock the Celeron to give me a pretty good system.

So, that's what I did and I got the CPU running fairly stable at 1.5ghz. It failed once, which I am fairly certain was due to the graphics card, so I realised that I needed to cool the system completely.

So, I'm designing a really good cooling system for the graphics card, am doing a major case modification but also, I want to make the CPU as cool as possible and I think one of the ways to do that, would be to have the fan running at its rated speed, which is 4800rpm. At the moment it's running around 2555rpm.

So, since the sensors on the MB are limiting its speed, then if I connect it directly to the PSU, it'll be running at it's rated speed and since I'll know that its 4800rpm, then I won't need any sensors, and things will be nice and cool and the goal is a 1.6ghz system for very little money.

Michael.

 

[Mist]

They cable connectors are probably exactly what I need, except that over here, we don't have Frys or Radio Shack and the only similar place doesn't have these items.

So, I'm going to rig up a test fan and if that works, then I'll go ahead and do it with the one we've been discussing.

Michael.

 

[Mist]

Actually, one of my friends across the pond is going to send me one of these cables, so I can't wait!!

I'm going to do a section on my website about all the mods and cooling and stuff that I'm doing.

Like I say, the goal is a stable 1.6ghz Tualatin Celeron.

If it works out, it may even go a bit higher.

Michael.

 

[Mist]

Actually, one of my friends across the pond is going to send me one of these cables, so I can't wait!!

I'm going to do a section on my website about all the mods and cooling and stuff that I'm doing.

Like I say, the goal is a stable 1.6ghz Tualatin Celeron.

If it works out, it may even go a bit higher.

Michael.