Couple of hardware Qs - Monitors and fans...

[Borkunit]

I have finally gotten to the alpha testing stage - guts are in the cabinet and I have been doing my burn in and a good bit of game playing to make sure things are working. 

I have a fan in the top of the cab, venting out.  It's powered from the mobo supplemental fan port.  The fan is spinning a bit faster than it needs to be and is somewhat noisy.  Can I run a rheostat inline so I can adjust the fan speed, or is this going to draw too much current and fry something?  If I hacked a connector and ran it straight off the power supply, would I be able to do this?  I am using pretty thin wire, so it won't be able to handle a lot of juice.  Anyone else have a solution for this?

As with most cabs, the PC monitor is mounted on an angle.  It has been working fine until last night.  I quit the front-end, back to Windows desktop with the expectation that the screen saver would come on and the picture tube would go into "standby" mode.  I came back, and indeed the tube was powered down in standby mode.  When I moved the mouse to try and get it to power back up I just kept cyclically clicking as though it was trying to kick out of standby but failing.  Powered everything down, let the monitor sit, but it still just keeps doing the same thing.  I am wondering if this could possibly have anything to do with the mounting angle.  It's a bit of a stretch, but I figured I'd look into whether mounting angle causes problems with anyone else.  I have a backup monitor that I am going to swap in...  We'll see if it dies.

Thanks in advance for any advice!

[Jeff AMN]

I don't have an answer on your fan noise, but I've never heard of angle affecting a monitor in that fashion. I guess others might be able to offer their own anecdotal advice, but I doubt you'd see so many cabinets with angled monitors if it was an issue.

[Borkunit]

Yeah, good point... Most likely just one of those annoying coincidences...  Good thing I have a backup monitor!

[SavannahLion]

It's usually best not to add anything between the fan and motherboard if the fan is powered directly from the motherboard. I've seen builders do it, but I've eschewed that design since I noticed one of my motherboards in an overvoltage situation trying to run the fan at a higher speed. Got rid of the pot and the overvoltage problem went away.

If it's a three wire fan, it's possible, depending on motherboard model, to control the fan speed via software. A very common feature with laptops.

Three wire fans can be plugged in to the PC supply directly, just don't use the (off the top of my head, test it with a battery) yellow wire. You can add a pot with that set up. They also sell hardware thermostat controllers that adjust fan speeds based on your settings. The caveat is that you can't make speed changes from the computer, you have to make changes manually.

Two wire fans are basically the same as the three wire versions, sometimes using the exact same hardware but no yellow wire. They're generally not controllable by the motherboard so they just run full speed.

Realize that the smaller the fan, the faster it has to turn to move air. The bigger the fan, the slower it needs to turn to move the same amount of air. Slower turning fans are also quieter. Whenever I need to move large volumes of air and the crappy PC fans aren't cutting it, I just hop down to the electronic shop and use what I can find. I have several really nice 10" baffled fans that can move over 400CFM on +5v. Perfect with a standard PC power supply.

[lanman31337]

how much do those 5 volt fans cost ya?  one of those would be perfect for me

[SavannahLion]

how much do those 5 volt fans cost ya?  one of those would be perfect for me

Hhmm... Good question. It's been about six or so years since I purchased those particular fans. I think I paid less than $15 for each one, new... probably because they were being discontinued or excess inventory or something. In retrospect, at that price I should've bought more. The closest the company makes in capacity and size is a 6-14v model that moves 550CFM but the closest in shape moves only 300CFM. I can't recall the name of the shop where I got them from at the moment.

What's cool about them is the company notches the blade which is supposed to reduce the noise factor a bit. I don't know if it works, but the notched blades look pretty cool in my book.

I originally bought them when vertical blow holes on custom PC's were still in vogue. I created a mock-up then I realized how utterly ---smurfing--- stupid and useless vertical blow holes were and dropped the project entirely. I eventually installed one in Badtz Maru custom case mod I was creating, but pulled it out before my psycho ---smurfette--- of an ex took the computer. Last I heard, the PC melted. Guess I should've declocked it.  Then I tried it in a radiator design, but ran out of money before I ever finished. 

Oh well. I misplaced them in a box with all the other weird components I collected over the years. Somewhere in a box, I have a pair of 10" fans, a pair of treadmill motors, some 120v 80mm fans (WTF was I going to do with those?), glowsheet samples (that I could never get working), and a bunch of other stuff.

[SavannahLion]

Come to think of it, I don't accurately recall if the fan is rated for 400 CFM @ 5v or 12v. I do clearly recall it moves at least 400 CFM and it operates perfectly with a PC PSU.