Overclocking a CPU fan

[The Coolest]

I want to overclock my super orb by putting more volts through it(CPU Temps idle: ~53C° full load ~57C°. I know its dangerous to fan but I don't care.) so I was wondering wich component should I add a resistor or something else? If I want to raise the voltage on the fan

[Monaco]

Hmm good question. A PSU puts out a +12V and a +5V lines. I know you can get +7V, but to get more than 12V? Some kind of stepper perhaps? That would yank more amps, too, maybe fry the fan header... I'm gonna flip thru a component catalog and see what I can find.

I thought I'd been around; but this has never occurred to me before!:)

PS a new, better HSF is probably the best bet here!

[The Coolest]

I have this prob that I can't get any new fans in the near two weeks and I want to try and overclock an old fan I got to see how it goes, I want to connect it to PSU, not the headers

[Monaco]

right on that's a good idea. Well I flipped thru the handy RadioCrack catalog cuz u got me thinking I want to try this. And... How are you at circuit boards?:D As far as I can tell you'll need to build a little circuit to accomplish this. I'm just a hobbyist not a pro, but AFAIK there is no little doo-dad you can stick in the line to raise the voltage easily. At the least you'll need some kind of coil and a controller.

I'd do this- look around the house for an old AC-DC converter, a wall wart. I got a few here that uotput 14V and one that does 25V just rotting in the junk drawer. Just cut off the end, strip the wires, attach to fan, plug 'er in and cross fingers;) .

Might wanna try the Mod your Orb route; I've seen tons of improvements to those thing for practically free.

If anybody reads this and sees I am wrong PLEASE post and tell me. I hate giving cr4p advice.

[The Coolest]

thx

[Quaky]

Search the -5 volts wire of your PSU, hook up the positive line of the fan to the +12 volts line, and the negative one to the -5 volts wire. This way the fan will get 17 volts. Plz note that the fan won't last for very long. You might want to change the fan with a bigger/higher cfm fan instead.

You could blow up your PSU if the fan's coil melts and shorts the PSU. I wouldn't do it, but I can only offer advice. Do whatever you like man! :D

[Monaco]

Quaky, sounds like a variant of the +7V "trick" to me. I've never gotten that to work, either. The PSU just turns off when I try it. What's the deal here? It looks like it can't possibly work, but everybody does it except me. What does a PSU need to have before this kind of voltage will work? Or is it a hit or miss thing? Seems like some kind of short protection.

17 is fine, but I just want 7!!

[It_The_Cow]

Originally posted by Quaky
Search the -5 volts wire of your PSU, hook up the positive line of the fan to the +12 volts line, and the negative one to the -5 volts wire. This way the fan will get 17 volts. Plz note that the fan won't last for very long. You might want to change the fan with a bigger/higher cfm fan instead.

You could blow up your PSU if the fan's coil melts and shorts the PSU. I wouldn't do it, but I can only offer advice. Do whatever you like man! :D You could also use a 12 volt line and the -12 volt ground on the motherboard connector. The label should say something about it, and if not, it's a color of its own. Even the dinkiest fans can push some air

[Crazy Jayhawk]

Originally posted by Monster of Rock
Quaky, sounds like a variant of the +7V "trick" to me. I've never gotten that to work, either. The PSU just turns off when I try it. What's the deal here? It looks like it can't possibly work, but everybody does it except me. What does a PSU need to have before this kind of voltage will work? Or is it a hit or miss thing? Seems like some kind of short protection.

17 is fine, but I just want 7!! Check your connection. Same thing happened to me, and it turned out the +5V was in contact with the case, which caused a short circuit and turned off the computer before damage could be done.

[Monaco]

That's not it. I'm trying it (again) using just my spare 350watt ATX and a fan on my wood desk. No shorts here! When I make the connect, it dies. Connect and then turn it on, and nothing happens until disconnect the fan and restart the PSU.

Arghhh.

[Crazy Jayhawk]

Originally posted by Monster of Rock
That's not it. I'm trying it (again) using just my spare 350watt ATX and a fan on my wood desk. No shorts here! When I make the connect, it dies. Connect and then turn it on, and nothing happens until disconnect the fan and restart the PSU. Arghhh. Probably a screwed up PSU then. I'm running two fans at +7V without any trouble.

[The Coolest]

Originally posted by Monster of Rock
Quaky, sounds like a variant of the +7V "trick" to me. I've never gotten that to work, either. The PSU just turns off when I try it. What's the deal here? It looks like it can't possibly work, but everybody does it except me. What does a PSU need to have before this kind of voltage will work? Or is it a hit or miss thing? Seems like some kind of short protection.

17 is fine, but I just want 7!!

I once put the black wire to -5 by accident and got the same resauly by comp shutting down.

[Veland]

I'd go for a AC DC transformer hooked up to the PSU. The "wall warts" generally has very low amp output. Just remember to hook up a rectifier too, cause normal AC DC transformers don't do a good job of "straightening out" the power. The fan controller I'm currently working on will let me set the fan voltage from 1,2 - 15 volts.

But there are also some DC DC converters that will give you more power, but their somewhat expensive, draws some amp, and generate some heat.

Good luck!

[lennytiger]

I have to say an AC DC conv is the best way to go if you wire somthingg to your PSU it could mean fatal injuries to either yourself or your wallet when you have to buy new pc components. In the UK we can buy amn ac/dc adapter which can vary the voltage between 5 and 25 volts, it works great and you don't screw the PSU up!!!!!:)

[maha_x]

Originally posted by Crazy Jayhawk
Probably a screwed up PSU then. I'm running two fans at +7V without any trouble.

No, as said many times on other threads: Yer PSU is not designed to work that way. The manufacturer does not offer that 7V as a feature of the PSU. Some PSUs can cope with it, some cant. But generally it is not anykind of official feature. The PSU manufacturers have notified them selves that connecting 12V and 5V can have unknown affects on yer PSU. And its void varanty also.

Yer PSU is perfectly good and working even tought it might not support the 7V hack. It not working is actually a safety feature, as normally this would mean that some device in yer mobo is broken and shortcircuitin yer PSU.

[Monaco]

Yeah maha_x, that's what I thought. Thanks for clearing it up. I guess some PSU have reverse-voltage or whatever protection, some don't. And apperently, all 4 of mine that I've tried it on do:D

Hey Veland- a wart will ouput up to 2 amps easy, if it's a good one. A CPU fan needs, what, a tenth of an amp? I think he'll be ok:)I've never had problems with fans being unhappy with chunky square wave current, they still spin for me. I'm super curious about your fan controller you are makeing however, that sounds really cool. PM me if you feel like telling me about it, I'd love to hear it.

word-

[Crazy Jayhawk]

This might not apply to your situation, Monster of Rock, but here's something else to consider. Some fans have metal bodies. My 120mm does, for example. It's separated from the case by a plastic bracket and it doesn't come in contact with other electronics. However, if I ran that fan at 7V with the body touching the case I'd short something out.

Just a word of caution for anyone else trying this. :)

[Monaco]

That's a good idea man. Some of my fans ARE metal-casing units; I'll be on the lookout for what you mentioned. I'm pretty sure my PSUs just don't like the trick tho-- too bad for me.

[Malpine Walis]

Originally posted by The Coolest
I want to overclock my super orb by putting more volts through it(CPU Temps idle: ~53C° full load ~57C°. I know its dangerous to fan but I don't care.) so I was wondering wich component should I add a resistor or something else? If I want to raise the voltage on the fan

There are circuits that output a voltage which is a multiple of a given input. For example 5vdc x 3= 15vdc. Or if you did the 7 volt mod, you could double that for 14vdc.

Radio Shack has some books on basic electronics that might have what you need. You might try the following:

Getting Started in Electronics
Cat.#: 62-5004

TechRef, 5th Edition
Cat.#: 920-2930

[RoadWarrior]

I've seen quite a few larger fans, like bigger than 60mm, that say 12-16v nominal on them, so if your -12v line has enough beef you could take between -12V and +3.3V and still be in spec.

BTW, not sure just trying an ATX supply on a desk with just the fan is enough draw to start up the supply properly.

Road Warrior

[The Overclocker]

have a look at this article: http://www.overclockers.com/tips808/, this is probably the quickest way but not as need, another idea is to use a variable transformer which, although expensive. will let you control the speed as well. (please not you can do this if you use the -12v as you place a variable resistor in one of the power lines - but it will only let you do dowsn to 12v unless you use a dual put to control bot sides)

[JFettig]

broun is the -12

so for 24v go with yellow+ and brown-

but check the amps on it, it mite not be enough, and mite blow you apart.....

[Roger24]

Originally posted by maskedgeek
broun is the -12

so for 24v go with yellow+ and brown-

but check the amps on it, it mite not be enough, and mite blow you apart.....

I tried that. The PSU refused to turn on with the larger fan, but it worked with the 120mm fan. That PSU has 0.8A for -12V

[T'wolves]

How many amps can you you get when you "overvolt" something, if my +12V is 8 amps and my -12V is .5 amps, how many amps can I draw maximum with a 24V set up?

[RoadWarrior]

You can only pull as many amps as the least rail can source, so in your case o.5A 500mA max, however, allow 50-100mA for every serial device you have running because your serial ports use the -12v line.

regards,

Road Warrior