Help with custom notebook cooler

Hi. I would like to power a 120mm desktop case fan though a usb port on my HP docking station. I don't even know where to start

I want to make sure that I get full power to the fan without harming my docking station (or worse, my laptop). This will be a stationary cooler for home use. If powering it through the docking station is too risky or difficult then I would be happy to power it through a standard AC wall plug.

Please help as I have know electrical know-how what so ever.

The following are links to the fan I want to use and the docking station that I'm currently using...

Scythe DFS123812-3000 "ULTRA KAZE" 120 x 38 mm Case Fan
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185054

HP ES631AA#ABA Notebook QuickDock
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185054

I am planning on strategically placing this fan directly under the vent on my laptop. It's airflow is 133.60 CFM and I will be placing it in a cutout hole in my desk so there will be absolutely nothing under it obstructing the airflow. It will be sucking air from the vent and blowing it under the desk. Let me know if you think this will provide effective cooling or not. Thanks.


..........
HP dv9700t CTO
Intel 2.2Ghz Dual Core
2GB RAM
Geforce 8600M GS
2 x 150GB Hard Drives

 

you will want to make sure the vent you are sucking from is actually blowing air out rather than sucking it into the case.

USB ports only provide 5volts of power. i reckon this fan will need more like 12v. hooking up 2 USB's would be possible, but i doubt you need anything like that much power through a small vent anyway.

using the power from the usb should not damage the laptop, unless you wire it wrong.

my last thought is: why the extreme measures to cool it? does it really need it? have you checked the temps using HWmonitor? so long as the graphics stays below 85-90, processor stays below 80-85, HDD stays below 60 under load its pretty safe.

 

Thanks for the reply...

If I hold my hand under the vent when I turn on the notebook (and the fan spools up) I can feel it blowing air. I'm assuming this means that it is not sucking air into the case.

I've decided to go with the overkill fan. It's not that expensive and I don't mind plugging it into the wall. If it's overkill then oh well. If I'm gonna do a custom cooling solution, I might as well go big. Now I just need some help with the wiring and what kind of power adapter to buy.

Please help. Thanks.

P.S. The temps don't go out of the zone you specified, but I would like it to run much cooler as I have it running 24/7 when it's at home and during the summer, my room temperature is rarely below 90F so the laptop will be running hotter than it is now.

 

ok, a couple of thoughts. have you measured the size of the vent under the laptop? if that fan is too big for the vent, it will just be sucking on casing, making a lot of noise and not adding anything much really.
also, im not convinced you need that much air flow to achieve this kind of cooling.

so you got a few options: get a smaller (80mm) fan and therefore most probably more energy efficient, therefore higher achievable RPM, and run it from the 5v USB connection,
or go for the 120mm BEAST running from 5v and just have it running at a lower RPM. i doubt you would want/need it running full speed anyway.
or you can wire the 120 to the wall.

you will probably want some way to vary the fan speed, especially if you run it from the wall. having that thing running full speed all the time will drive you nuts. you could either get a fan controller as used in desktop computers, or just use a very crude variable voltage resistor inline on the live wire.

raided from wiki:

Typical Fan

Black: Ground
Red: +12V, +5V
Yellow: Speed sensor wire -usually open collector output (RPM)

it seems like USB power is the red cable, ground is the black, so its the same deal as the fan. you want to ignore the white, silver(?) and green cables in the usb plug. you might want to cut and tape them off to prevent "USB device malfunction" errors. the red and black cables can be soldered, shrink wrapped, or electrical taped. id advise tape, cos its easy. lol.

i dont know anything about wiring to a mians plug, but im guessing you will need a 12v dc power supply, but i have no idea what current it would require. it will be fan specific, so you would need to research that yourself.

the other option is to get a USB powered fan. they do exist, and are pretty cheap, but i doubt they are particularly good quality or power.


so there ye go! i think thats a fairly complete guide. just shout if theres anything else

cheers

 

Thanks. I already ordered the "BEAST". lol. I figured that it would provide at least the same amount of cooling as an 80mm and MAYBE more, which is why I went ahead and ordered it. However, if you're saying that the 120 will actually provide LESS cooling, then I'll go ahead and order an 80. Please let me know. Thanks again.

P.s. I think I'm gonna do the wall option without a controller (I will add a switch though). My room is very noisy so it won't bother me. Plus I'm used to my old desktop that made SERIOUS amounts of noise However, I will try the usb first and see how it does as I have an extra cable. Do you think that my old power adapter for my bluetooth will work as far as the wall option goes?

 

I'm an idiot. I did some research and the wiring and amperage thing is pretty simple. I should've just done that in the first place instead of bothering you. Sorry

BTW...I found out that a usb port provides only 500mA while the BEAST draws 600mA so usb is out of the question in this particular instance.

I still would like your opinion on whether the 120 will provide AT LEAST the same amount of cooling as a smaller fan rather than LESS cooling.

thanks again.

 

oh yeah it will cool it fine, but it will be quite a lot louder than the 80mm cos its sucking case too, but if the noise isnt an issue it will be fine. as for wall adaptors.... i honestly dont know. you will need to have a look for a power adapter that is as close to 12v and 600mA as you can find. if its slightly too high you will need a simple resistor, and if its too low youl just have reduced power.

im not sure what effect having 100mA less current on the fan will do. it will most probably be fine, theres plenty of people who have used old computer fans and USB power before on instructables.com, but ive not seen any on there using a 120mm fan. give it a go, if it doesnt work, wall it or put an 80mm fan on instead. i cant see it frying your USB port.

 

I was talking to an electronics major at school and they said that a fan pulling MORE current than what is supplied by the usb port, could damage the laptop. Most of the 80mm desktop fans (not all as I've found through searching newegg) run on 500mA or less.

I bought a power adapter that will handle the job. It's 12v and has some extra current. I was told that having more current won't hurt as the fan will only draw the current that it needs.

And I found out that the laptop fan actually DOES suck air into the case. I will no longer be placing a fan under the main fan vent. I had already ordered an additional 80mm fan before figuring this out However there are two additional rectangular vents nearer to the front of the case (used as additional escape vents for the air being sucked in I'm assuming). One is vertical and the other is horizontal. I measured them and, as it turns out, one is 120mm long and the other is 80mm long. I've already ordered two fans exactly that size, so I'm just going to place each under it's respective sized vent. I'm hoping that provides some good cooling.

Let me know what you think. Thanks again for helping out with this.

 

it would probably be better to put one of the 80mm the fans under it and blow air into the laptop, since its easier to create additional pressure than negative pressure.

is there only one vent in the bottom? if theres more, the 120mm fan might still be of use under a different vent, or you could put it behind the laptop, and push air under the entire thing, just to aid circulation even more.

something like this? http://www.instructables.com/id/Pwr-laptop-cooler/