A possible cause of failures - dust

Over weeks and months, exhaust case fans and power supply fans can suck in dust through the crack between the tray bezel and the faceplate of the optical drive, unless the drive has a gasket to seal the opening. I’ve attached a photo of my case; an old generic DVD-ROM is at top, while my relatively new Lite-On LTR-52246 is at bottom - apparently clean.

Some time ago, I posted here about a problem I was having with repeated failures of Lite-on CD-RW drives after a few months. The post is at http://forum.cdfreaks.com/showthread.php?s=&threadid=72389 and I won’t repeat the issues here, other than to say that no firm conclusions were reached, but the consensus on the most likely culprit was case heat (the drive was at the top of the case).

Today I read the following post on Silent PC Review (a useful site for anyone interested in reducing PC noise):
http://forums.silentpcreview.com/viewtopic.php?t=7630

Note that the relevant comments are quite a ways down - search for “Yamaha”. The discussion moves from case fans to dust being sucked into optical drives.

A similar post is to be found at http://forum.cdfreaks.com/showthread.php?s=&threadid=74619 - I’ve just commented on that post, and thought it might be useful if I posted the information to the Lite-On forum as well, as in spite of many people contributing before, no one suggested dust as the culprit.

As my own newish Lite-On appears dust-free, and works ok, I can’t say one way or the other that dust was involved with previous failures. And my DVD still works OK. It would have been interesting to learn if a cleaning would have helped.

But I think than in evaluating failures, we should be careful to note dust intake issues.

My case has internal negative pressure and sucks in dust like a vacuum cleaner - well, maybe not that quickly, but it’s a real issue. I’m going to be sure that my next system has positive pressure in the case.

Hi,
I remember your posts very well. and thank you for posting your research. You are 100% correct that negative case pressure can kill optical drives. Case pressure needs to be balanced to avoid this problem. As a rough measure of airflow, I just add up the total rated volume of my intake and exhaust fans, and try to keep just a little bit of negative pressure. I used to have a huge 120mm monster on the back and nothing else. Untill I discovered the rather alarming drifts of dust in and around the optical drives.
Now I never see this.
Actually, i don’t think that positive pressure is the solution, or that negative pressure is the problem. It’s just the fact of airflow through places that it shouldn’t be. Any airflow will result in dust being deposited, so the solution is to direct the airflow and keep it to a minimum while doing the cooling that is required. If you wish to increase the flow into the case, you have to create a way to get in in there (intake fans) so that it doesn’t flow around the drives.

I’ll add that in my main computer; I have two intake fans in the front of the case and two exhaust fans in the back (one regular fan and one in the PSU), so my case pressure is slightly positive. I have never noticed deposits of dust in and around my optical drives, either, and I live in a very dusty environment.

Originally posted by oldabelincoln
A similar post is to be found at http://forum.cdfreaks.com/showthrea…&threadid=74619 - I’ve just commented on that post, and thought it might be useful if I posted the information to the Lite-On forum as well, as in spite of many people contributing before, no one suggested dust as the culprit.

In your thread concening LiteOn reliability(http://forum.cdfreaks.com/showthread.php?s=&threadid=72389&perpage=25&pagenumber=2), I told that I had similar issues with my 32123S and that I solved the whole problem by simply cleaning the drive, but my quote stayed unanswered as you were too busy searching THE scientific reason of poor reliability of LiteOn drives.

Fredsky.

Originally posted by fredsky
[B]In your thread concening LiteOn reliability(http://forum.cdfreaks.com/showthread.php?s=&threadid=72389&perpage=25&pagenumber=2), I told that I had similar issues with my 32123S and that I solved the whole problem by simply cleaning the drive, but my quote stayed unanswered as you were too busy searching THE scientific reason of poor reliability of LiteOn drives.

Fredsky. [/B]
So you did. By that time, I had stopped checking responses, as my new drive was running ok, responses had tapered off, and I had other issues to worry about.

But I have no excuse for missing it the second time around, when I reviewed the older thread before posting this thread. Interestingly, on the earlier thread, the post just before yours (another one I missed by absence) tried a cd cleaner and other anti-dust measures with no luck.

Originally posted by rdgrimes
Actually, i don’t think that positive pressure is the solution, or that negative pressure is the problem. It’s just the fact of airflow through places that it shouldn’t be. Any airflow will result in dust being deposited, so the solution is to direct the airflow and keep it to a minimum while doing the cooling that is required. If you wish to increase the flow into the case, you have to create a way to get in in there (intake fans) so that it doesn’t flow around the drives.
I think it’s a bit different.

Airflow in to or out of a computer case is caused by pressure differentials - fans are there to create a pressure differential. Of course, airflow certainly causes pressure differentials - that’s how planes fly, and how fans produce a differential.

But if you have lower pressure inside the case than outside the case, air will flow into the case through every available opening, regardless of the details of the major paths that the air is taking into the case, within the case, and out of the case. If the pressure inside the case is higher than outside the case, air will flow out of the case through every possible opening.

Putting in an intake fan certainly directs the flow all right, but that’s not what keeps dust out of the case if that’s the setup. What happens is that intake fans add positive pressure to the case. Intake fan(s) moving [b]less[/b] air than the exhaust fan(s) will offset the negative pressure caused by the exhaust fan(s), but still leave a negative pressure inside the case. Intake fan(s) moving more air than the exhaust fan(s) will cause a net positive pressure inside the case. If you’ve got positive pressure, and a reasonably clean case with filters on the intake, you’ll be blowing reasonably clean air out through the optical drives. Probably not a lot, but it will be clean.

If your pressure is just slightly negative, you will still be drawing air in through the optical drives. If you see little dust there, then you are just not drawing much air in through them, which is certainly consistent with a slightly negative pressure.

What advantage do you see in a slight negative pressure?

Abe

you’ll be blowing reasonably clean air out through the optical drives. Probably not a lot, but it will be clean.

Unfortunately, no so. Any moving air will deposit dust. Unless you’re using effective filters, it all has dust in it.

Originally posted by rdgrimes
Unless you’re using effective filters, it all has dust in it.
I agree. And I said

“If you’ve got positive pressure, and a reasonably clean case with filters on the intake, you’ll be blowing reasonably clean air out through the optical drives. Probably not a lot, but it will be clean.”