Mounting fan in non-standard frame

markjia · Post by **markjia** » Tue Jun 29, 2004 3:55 pm

I'm trying to replace the fan in my old Dell machine, but the problem is that the mounting is not standard. It uses a standard 80mm fan (the stock one is an NMB), but instead of securing the fan directly to the case, has this plastic frame to install the fan in. The frame is then snapped into place on the case.

The problem is that I can't manage to dismantle the frame to replace the original fan with my new L1A. The holes were the hooks go are roughly where screws would normally go, but a little closer together, so screws won't work without drilling new holes.

For the momment, I am using cable ties to attach the fan...but this means that there is a substantial gap between the fan and the case. Will this space make for poor air circulation (I've removed the fan grill on the case though)?

Any suggestions for a better solution? Perhaps someone know a trick to removing the fan casing? In each of the holes, two small plastic rods (one coming from each direction) are locked together with two rows of small interlocking teeth on either half of the rod.

greeef · Post by **greeef** » Wed Jun 30, 2004 4:20 pm

just fill the gap with something soft and rubbery and deal with the better isolation and noise reduction. Chuck that fan mount away.

Michael Dooley · Post by **Michael Dooley** » Wed Jun 30, 2004 5:52 pm

I've replaced 80mm fans on two Dells that I have, an old 4100 and a newer 8250. The 8250 fan was mounted in the detachable plastic frame with rubber EAR like devices so it was easy to replace. The 4100 was somewhat more difficult because the fan was (IIRC) firmly locked into place in some manner. It took a little patience to get the old fan out but it was able to be done. I think that I had to both push the fan out the backside of the frame while prying the frame a bit to unclamp from the old (noisy) fan.

What kind of Dell do you have? Any pictures? These things are made so that replacement is possible, right? Good luck markjia.

rtsai · Post by **rtsai** » Wed Jun 30, 2004 6:05 pm

Yes, what kind of Dell machine, and why do you want to replace the fan?

I have a Dimension 8300, which I think is the same (fan- and frame-wise) as Dooley's 8250. Like yours, my also came with some NMB 80mm fan.

When the fan ramps up (e.g., running Folding at Home, gaming), the worst offender is actually not the fan. The offending howling noise actually comes from the plastic green duct that is attached to the black frame (e.g., if I remove the green duct the noise goes away). I think there is some kind of wind-tunnel or airflow effect around the edges of the duct. I don't think the duct is rattling (it's a "howling" noise).

I don't have any complaints about my stock NMB fan. My case sits on my desk; the back is about 1m away from me and I don't hear it above the background noise (I live in an urban high-rise, so ambient isn't exactly "quiet").

Michael Dooley, why did you replace your 8250 fan? Do you not suffer from howling duct noise, or maybe you don't waste your time gaming?

Michael Dooley · Post by **Michael Dooley** » Thu Jul 01, 2004 7:38 am

I live at the base of a redwood forest with ferns and mossy stumps and a nearby seasonal brook. I awaken to bird life chattering away each morning. Ambient noise is quite low.

The loudest thing in my office is the clicking of the wall mounted clock. The Dimension 8250 used to compete with the clock. Like rtsai's computer, my Dell sat on my desk and the back of the case was less than a meter from my ears.

I installed a Zalman 7000 alcu with a fanmate and replaced the NMB with a panaflo. The noise dropped quite a bit. When I cut the grid from the case where the PSU exhausts, the Dell became even quieter. I eventually replaced the Dell with a ME6000 machine that has only one fan - a Seasonic 200 watt PSU that exhausts all the heat. I gave that Dell to a daughter - she thinks that its quiet.

So is gaming a reference to Solitaire or something more involved?

rtsai · Post by **rtsai** » Thu Jul 01, 2004 9:14 am

Michael Dooley wrote:I live at the base of a redwood forest with ferns and mossy stumps and a nearby seasonal brook. I awaken to bird life chattering away each morning. Ambient noise is quite low.

Lucky you. I've been going to sleep to the rhythmic jackhammering of the various mysterious public works projects in this neighborhood. They don't jackhammer during the day because it would get in the way of all the traffic.

Michael Dooley wrote:I installed a Zalman 7000 alcu with a fanmate and replaced the NMB with a panaflo. The noise dropped quite a bit. When I cut the grid from the case where the PSU exhausts, the Dell became even quieter. I eventually replaced the Dell with a ME6000 machine that has only one fan - a Seasonic 200 watt PSU that exhausts all the heat. I gave that Dell to a daughter - she thinks that its quiet.

How did you know that everything was still within safe operating temperatures? It seems the Dell proprietary mobo doesn't support the usual kind of temperature monitoring you can get with all the other motherboards. Is the only symptom of an overheated CPU a system crash? This black-box-ness is the final hurdle for me to overcome before I consider installing aftermarket stuff into my machine (dude, I got a Dell

).

Michael Dooley wrote:So is gaming a reference to Solitaire or something more involved?

I play way too much Enemy Territory (3D gaming)

. Usually my machine is quiet; the fan/duct gets howling when doing anything CPU-intensive (F@H, 3D gaming). Hence my worry over doing any kind of computer reconfiguration that would differ from the Dell design assumptions.

Michael Dooley · Post by **Michael Dooley** » Thu Jul 01, 2004 11:07 am

rtsai wrote:How did you know that everything was still within safe operating temperatures?

My wife picked up a baby thermometer that evdently works off of infrared. Normal use is to put this thing in the child's ear and click a switch - the reading (either F. or C.) appears on the read-out. I pointed it at various things and got instant readings. I didn't want to monitor continuously as that would involve too much time. I just needed to see if things were working well enough to shut the case and go on with other things. After a week's worth of checking every now and then, I gave the device back to my wife.

My normal use of the machine is CAD work, mostly 3D stuff. Not really CPU intensive unless I'm doing a lot of boolean operations. Rendering models is probably more graphics intensive but not on the order of even the most primitive gaming that you might do.

My computer usage is probably light by most standards, but I go at it for over eight hours a day. And I love the absence of noise.