Wednesday, January 26, 2011

Procrastinating With Computers

I have a lot of projects going on right now, my regular jewelry and machine tool stuff, an air rifle that’s about 50% done and a lengthy kitchen semi-remodel. But sometimes you have to work on projects for the heck of it. Out in the “barn” I have a Dell Optiplex 270, in the small form factor. We use it to watch Netflix and Hulu when working or running on the treadmill. Unfortunately the other day it wouldn’t power on, and the power button was blinking an ominous yellow.

The Motherboard looked fine (some Optiplexes had bad capacitors) so I assumed it was the power supply. Being a small form factor a new power supply would cost as much as the used Dell had cost. What I ended up doing was mounting it in a Dimension 8200 case, figuring that at some point I’ll mount the 8200 motherboard in another case or just leave it around to trip over. The 8200 cost $3000 in 2002, now it’s not even worth $30.00, nor is the Optiplex. I get all these old Dells at the OSU surplus sales. The Optiplex has a P4 3.0 Ghz and 2GB of RAM, so it will run Hulu fine. That’s about the minimum antique processor for internet video, according to my unscientific tests. But I digress.

The main problem with putting the Optiplex motherboard in the larger case is that there was no way to use the existing 8200 fan and shroud from the case as it hit the CPU fan, and the Optiplex CPU fan has a shroud that wouldn’t reach the rear of the case. So it was just blowing hot air around the inside of the case. Still awake? No? go back to sleep.

I decided I’d mount an old case fan somewhere along the back grill to suck more air out of the case and hopefully provide better cooling. Unfortunately the motherboard only has one fan plug, which was used by the CPU cooler. I could have bought an adapter but decided to waste some time. I dimly remembered buying some female 4 pin molex connectors at a yard sale 12 years ago, searched for them and found them.


The three pin fan connector.


Male Molex from a power supply.


Female Molex and pins.


Wires stripped. (I ignored the blue fan sensor wire).


Pins crimped on.


Checking to make sure I get 12V, although at this point I thought Red & Black was 12V. It isn’t. I should have checked wikipedia first.


Pins inserted in the female connector body.


Optiplex in a larger case.


Here’s the fan wires and connector used by the CPU fan.


Plugged my new fan wires into a spare plug coming from the power supply.


(Can’t use the flash or you won’t see the blur). The fan spins. But it seems to be spinning slowly. This is when I discovered my voltage error.


I rewired so that I was getting 12V rather than 5V…much better. Now all the hot air is being sucked out of the case as fast as it’s produced. I ziptied the fan to the case grill for now, leaving it to run for a while to make sure there are no problems.

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