Old computer noisy, CPU fan spins up

[mikepukmel]

Got it thanks Enzo. I think I have another that will fit.

[bob p]

I would have kept one of them, but could not get Linux device drivers for it.

If you're familiar enough with linux to roll your own kernels, Linux doesn't use "device drivers" per se. Linux uses kernel modules. The major distributions ship with a fat kernel that has most of the "drivers" built-in or accessible as modules for the less common hardware. But there are hardware supports that will get left out if the hardware is old enough. But that doesn't mean that the support isn't there. With Linux you don't go to the device manufacturer for a driver like you do with Windows, you go to the kernel management script and build your own kernel to include the modules that you need for your oddball hardware. Chances are that you can build your own kernel and select modules for really old hardware, or just install an old (vintage) version of Redhat to run on your old boxes.

When I did Gentoo development I focused on building compilers and toolkits to optimize execution speed on old hardware.

[g1]

At least have a look at your supply caps for any bulged domes etc. So far your description of the symptoms matches what my defective supply was causing right up till the whole thing just wouldn't run anymore.
And agree with Enzo about a noisy fan not being able to do it's job properly, had that problem with our fridge.

[mikepukmel]

Bob, thanks for the Linux tips, didn't know that! Wish I had saved a couple of the old carcasses. There was one with dual pentium somethingoranother. It was about 1997 or 1998 pieces parts computer. I will look into building linux, that sounds like a gas!

***

Got the old fan out, cleaned the heat sink, REALLY cleaned off the section that sits on the CPU, and reapplid a nice thin coating of heat grease. Aaaaaand, another piece of my hadywork, i cleaned the fan so well that I cleaned a blade off the fan, snapped it right off. <big frown> I was using all 10 thumbs and 7 index fingers to accomplish that task.

Went down to best Buy, nope, their selection of 3 fans didn't cover it. So, all the way down to Microcenter, its a big computer and related electronics 'stuff' place in Cambridge MA, about half hour or 40 minutes down the road. They have a bazillion different fans. Of course, the blasted connector is DELL proprietary 4 wire PWM, so none of connectors on the other 4 wire PWM fans (they have like at least 10 different ones) looked like anything close. I was just about to give up, and thought, ok, the PWM is nice since it spins the fan down when not needed. But, what if I just put a fan in that runs all the time at the same speed. So, I picked up a $12.00 "always on" fan and installed it a little while ago.

So far, nothing has melted. And, no sparks or other indications of electronics giving up on me.


It puts out a significant multiple of the airflow that the old fan put out, even compared to the old fan at high speed. I can feel the air a couple of feet from the computer, never could do that before. And its not *so* loud.

So I think at least one problem, even though the bearing didn't feel gritty, the fan was not putting out enough air even at high speed, which you guys said above was a possibility, thanks.

Tomorrow, I will pop out the PS and check for bloated, leaking filter caps. Easy enough to fix those if they're bad, now that I have my fluorescent magnifying ring light.

[mikepukmel]

This I thought was bugged out: I took out the old fan, and the airflow arrow pointed towards the FRONT of the computer, away from the heat sink. Can that be right? Shouldn't the main CPU fan blow OVER the cpu heat sink?

This is interesting: after running the computer for a couple of hours, doing vital and critical work for humanity, if I reach my fingers back as close to the CPU as possible and touch the heat sink, its always much cooler than before. Even when the fan went into fits and tried to run away, the sink was always much hotter.

[bob p]

CPU fans typically draw free air and push it through the fins on the CPU heatsink, which also helps to force air along the base of the motherboard to cool the chipset and vreg. The only time I've seen pull fans is when there are two fans on each side of a heatsink in a push-pull configuration, like on the big coolermaster V series.

take a pic for us so we know what you're talking about.

if you want to reverse the flow of air that would be as simple as switching the polarity of the 12 volt leads. check the fan header pinouts in your motherboard service manual, available from dell online by download. compare that to your fan setup. the wiring will not be thesame.

[mikepukmel]

Steve, I mentioned replacing the fan, because here without the thing in front of me, it sounded like he might have a fan wearing down its bushings, causing it to be overly noisy when cranking, and cranking because it was no longer spinning at full volume and moving sufficient air.

Enzo, I think it was not pushing enough air, maybe something wrong inside the motor itself, even though the bearings felt fine (spinning by hand, gently with my fingers, wasn't grinding, felt smooth). the big aluminum sink is now running a lot cooler to the touch with the new cheapo fan.

[bob p]

Motherboard 4 pin CPU PWM fan connector pinout diagram @ pinoutguide.com

[bob p]

Enzo, I think it was not pushing enough air, maybe something wrong inside the motor itself, even though the bearings felt fine (spinning by hand, gently with my fingers, wasn't grinding, felt smooth). the big aluminum sink is now running a lot cooler to the touch with the new cheapo fan.

pin 3 provides the tachometer output. look at your fan speed in BIOS.

[bob p]

Of course, the blasted connector is DELL proprietary 4 wire PWM, so none of connectors on the other 4 wire PWM fans (they have like at least 10 different ones) looked like anything close.

Dell uses a 5-wire system, where the 5th wire has no connection. They move the tach from Pin 3 to Pin 1 and then reverse the order of pins 1,2 as they move them to positions 2,3. The result is that your +12V and Ground wires are not connected to the +12V and GND pins. They even change the colors just to fuck with you. I just cut the wires and splice as appropriate.

I don't like Dell. HP does this nonsense too.

Dell 5 pin Fan connector to standard 4 pin PWM Fan pinout diagram @ pinoutguide.com

[mikepukmel]

Bob, thanks, man, I looked and looked and couldn't find that info, exactly what I was looking for. The fans at Microcenter, about 1/2 of them had color coded wiring, and the other half the wires were all black. But with the diagram in your link, Im all set!

Why the heck would Dell make a 5 pin connector on the MB and cable, for 4 wires?

[Steve A.]

Enzo, et al: The CPU cooler on the vintage motherboard in this thread consists of a fan mounted on top of a block of aluminum cooling fins. The CPU itself controls the speed of the motor based on the internal temperature it senses. While the OP mikepukmel said that there was no program he could run to determine the actual CPU temperature in some of the 2006 vintage computers there may be settings for that in the BIOS setup.

I ran into the same problem as the OP in three different computers, mainly due to dust collecting on the aluminum cooling fins which allowed the CPU to overheat which triggered the CPU cooler fan to run at maximum speed, which is very loud so as to get your attention.

In troubleshooting your first question is whether the CPU is actually overheating or has its internal temperature sensor gone bonkers. One indication is how the white heat transfer paste looks when you remove the CPU cooler... if it doesn't look fresh there is a good chance that the CPU has been overheating.

One thing to check is the venting of the computer... is there plenty of air flow throughout the interior? In some computers the cooling fan on the power supply is a critical part of the venting as there are not a lot of other openings. I did look up the Dell model and it is a big tower so I doubt that venting is the problem.

I recommended getting an inexpensive refurbished business computer if the problem can't be resolved easily because for my 2009 HP Win 7 PC I ended up replacing the CPU and the cooler, fortunately at decent prices from Amazon and eBay. On other computers it has been tricky getting replacement coolers that are compatible physically and electrically (like the # of pins on the mobo connector.)

One good thing about getting refurbished off-lease business computers is that for the more popular models you might be able to get used parts you need later from the small businesses that refurbish and sell them. When the leases are up there could be 50 or 100 computers that are being replaced. The refurbishers might have to cannibalize 2 or 3 computers to come up with one computer that they sell on eBay. They usually keep a selection of commonly needed replacement parts just in case one of the computers they sell needs them. (They can do basic tests on the computers they sell but it is the end user who will be doing the final "real world" tests.)

Steve A.

P.S. A big thanks to Bob P. who is much more familiar with Dell CPU coolers than me! I've bought 4 refurbished Dell computers for myself and friends but have not had problems with their CPU coolers. Dell does have its own way of building things like the way it mounts hard drives which I guess makes it easier for IT to swap them out...

[bob p]

Dell and Compaq and HP all have their oddball way of doing things. Like proprietary fans/fan shrouds, hard disk mounts that required Torx screwdrivers, etc.

this reminds me of the old story about what's a truly IBM-compatible computer. Back in the day of the 86/286 boxes I asked a friend who worked in IT if I should buy a Dell, Compaq, Sperry or Zenith if I wanted an IBM-compatible PC. He told me to buy a Packard Bell, because the big names all changed things to make their computers have oddball proprietary interfaces in order to hook customers for after-sale support. They even changed their versions of MS-DOS to make them proprietary, recognizing the on-board BIOS, to do things like prevent future HD expansions without paying a fee. He said that Packard Bell didn't change things and kept everything at the generic IBM-compatible standard, which meant they were truly compatible while the 2nd tier brand names were not.

Today it's the same. Your basic ASUS or Gigabyte board is going to fit the generic standard while something from one of the big names won't. Like Steve said, Dell likes to do things their own way. the fan is a good example. There's no need to use a 5-pin header on a 4-wire fan, instead of the industry standard 4-wire header, and there's no need to go changing the order of the wires, but they do it anyway -- just so you can't buy a generic fan and you'll be trapped into buying an overpriced Dell fan when the time comes. to beat them you have to cut and splice wires, or remove and reorder the pins in the header. I keep a bunch of wires with male/female dupont connectors on hand for this sort of thing.

In this context, the commercial slogan "Dude, you're getting a Dell" takes on a whole new meaning. It's more like, "Dude, you're getting bent over."

while you've got the PC open, take it outside and blow out the dust with the exhaust from a vacuum. whatever you do, don't try that indoors.

[Mick Bailey]

You could see what monitoring is available for your PC by using the following utility - I just ran it on XP and it showed the CPU temperature;

Downloads - Open Hardware Monitor