YS Tech TMD Fan

Possible shorting out issue – Joe

I received this email from Clarpet:

Joe, thought I’d let you know that the YS Tech TMD fans were known to have issues where they would spin uncontrollably. I have a few theories related to switching power supplies that I believed to be the issue…. I may certainly be way off.

The reason I’m telling you this is that the fans were NEVER officially recalled by YS Tech and they don’t appear to have made any official public statement in regard to this. I was going to purchase a Swiftech MCX4000 from Crazy PC and noticed the TMD fan was the only fan option offered. I immediately called CrazyPC and asked if it were possible to order a different fan…they had no problem w/this.

I asked if they were aware of this issue and they stated that they were. I haven’t really heard much about the issue since, but I see that sites are now offering the YS Tech fans again, and the ONLY site I have found that makes any kind of statement that APPEARS to be related to the known issues is this from Crazy PC:

CAUTION: Make sure to insulate the metal housing on the TMD fan from any contact with metal. If you are using screws to attach this fan to a heatsink insulate the screws with rubber or nylon washers from contact with the metal fan housing.

What I’m wondering is this: Can anyone get an official statement from YS Tech on these fans? Are they now safe? If you must have a non-conductive washer to make these fans operate correctly, is YS Tech going to supply this? And lastly: Why is CrazyPC the only (again I believe this to be true) site w/this statement?

We asked Crazy PC about this and they replied:

The official statement of YS Tech is that the fans are not on recall and that they are not defective. If there is a problem with the fans they have stated that they will provide warranty replacements for defective fans. At any rate, the issues we’re aware of are:

1 – The fans are believed to have a large power draw at startup. The solution to this problem is to use a 4 pin connector with the fan. We supply all TMDs with a 3 to 4 pin adapter free of charge.

2 – The metal housing seems to cause some kind of short on some of the fans if they come into contact with either the case or the heatsink itself. The solution is to make sure the fan housing is completely insulated. We supply all fans with 4 rubber washers as well.

We decided that, provided the customers are aware of the issues, we would continue to sell the TMD fans.

I have a couple of these fans and tried to get them to spin out of control without any luck, including shorting out the metal housing. It appears that this is a very limited issue, but if you have had a problem with a TMD fan, please email me with specifics.

Email Joe


I purchased an MCX4000. The original fan that came with it, the moment I finished plugging it in the fan adapter on-board (3-pin), it started up. Spin spin, stops, and the fan started to smell, so I thought my freaking CPU got fried or something. But luckily it was just the fan.

Then I was too lazy to ship my fan back to where I ordered it from, so I went to a local computer store to pickup another TMD fan. And this new one has been working fine ever since I got it.

And NOTE, for both of the TMD fan, I’ve used the rubber washer between the fan and the heatsink. So maybe the Shorting issue isn’t the problem, most likely be drawing too much current, so much it kills the fan.

But ONE IMPORTANT thing I’ve noticed on the 2 fans had a different model number. The new one says 12v DC 2.02W, but I am not exactly sure what the original one was. I do remember the wattage was higher on the original one, and I can’t double check because I’ve refunded the old one. So maybe you can ask others who still has the original fan from the MCX4000 for the model number and wattage.


I’ve been running a 70mm 5600rpm TMD fan on my SLK-800
for about a good 2 months now. It has been plugged
into a 3 pin fan header on a Shuttle AK35GTR ver1.0
mobo without any issues to speak of.

Only thing weird
I’ve noticed is that MBM 5 and the BIOS reports the fan
to be running at 10,000-11,500 rpm but I know this
can’t be the case or it would be much louder. The fan
seems fine to me.

ed note: Apparently some TMDs have this quirk.


I had this exact problem. I use a YS Tech TMD 70mm fan on my mini-ATX case
blowhole I installed. I tried it out of the case and it worked fine.
Every time I would put the side panel on, the fan would seize.

I finally came to the conclusion that it was shorting on the case.
I installed some plastic washers between it and the case siding and now it
works fine!


I saw your article about faulty TMD fans and I thought I’d chime in with my experience. I purchased the medium-speed (4500 rpm) version of this fan from nexfan.com a while ago. I’m not sure of a date, but it was pretty much immediately after they started carrying them.

When I first installed this fan, I had absolutely no problems with it, except it stated that it ran at ~8000rpms. In about less than a month’s time, I started up my computer one day and I instantly blue-screened Windows 98 (I’m saying this as if BSOD’ing 98 is a rare occurrence 😉 ). I had my side panel off (though I don’t remember why…), and I noticed that the TMD fan was NOT spinning.

I shut down the computer, reseated the TMD fan wire and started back up. I decided to instantly go into the BIOS to make sure that the fan was spinning and to give my CPU time to cool down. My fan then worked fine…for a few days. The same scenario repeated itself. I took the fan off and switched to my original Evercool 70mm fan.

A few weeks ago I decided to reinstall the TMD fan, this time wiring the power to a 4-pin molex connector and the sensor wire to the motherboard. The fan did the same thing as before, only worse. Now the fan only spun at about 2000 rpms. I tried running the sensor wire to my other motherboard header – same readings.

I then took the fan out of my case and let it sit on my desk and run; it ran at ~8000 rpms again. I asked about it on the gideontech forums and someone suggested that it could be due to pressure in the corners when mounting…so I figured that was the problem. I haven’t tried using rubber washers, but when the fan was sitting on my wooden desktop, it still ran at almost twice its rated speed.

Hopefully this is of some help…


I’m having problems with my TMD fan (Swiftech MCX4000) but not running out of control; instead, it doesn’t want to start. I’ve tried both the 3 pin and 4 pin connections. I noticed my CPU temp went up above normal and when I checked SMART Guardian (it’s a SOYO MB) it showed the big zippo for fan RPM’s.

I opened the case and sure enough, it wasn’t spinning. I gave it a push and all was well until I shut down. Now every time I boot up, I have to manually start the fan no matter what connection I’m using. My PS is an Enermax 465 so I know I’m pushing plenty of power.

I bought the fan/heat sink combo in August from Cool Breez, I wrote them on Thursday to let them know of the problem. They are sending me a SUNON 80mm as a replacement at their expense (now that’s customer service!).

Until I read the article, I was unaware of any problem with the fan. Even without the fan, the temp only rose 4 degrees, but the Enermax is blowing directly on the heat sink so I’m sure that helped a ton. It’s a P4 1.6 overclocked to 2.13 (max for the MB) and it runs normally at 102 F with the Swiftech heatsink – not too shabby. MY problem is keeping my GF4 Ti4200 to stay cool.


First, let me say that I’ve had ZERO problems with my PD1270155B-2F “high speed” TMD. I used it on my Arkua “silent solution” HS model 7528 to keep my T’bird 1.33 cool. I was surprised to read that they are recommending they be plugged into a 3-4 adapter to the PS because I’ve run mine to the MB header (Soltek DRV4) without issue.

The fan came with a little piece of paper recommending that the fan be insulated at the mounting screws and I
did do that, but only under the heads of the screws, not between the fan and HS.


In this thread at HardOCP I posted this…

“I HAD one. On my MCX4000 sitting atop my brand new IT7 MAX. Powered it up for the first time, the fan spun for a second then the power kicked out. Kept doing it. Took the fan off and swapped it out with an 80mm and it fired right up. The YS Tech was SHORTING OUT on the heasink. Sent it back to Sidewinder Computers for a RMA exchange for a good 80mm fan.”

Mine shorted out on the heatsink…. and could have been worse according to the thread. One guy lost his motherboard because of the YS Tech fan!

BR Uwe/CoolHard at hartware.de

We heard about problems with the TMD also. In Germany, we
have no problems with them. I have 4 TMDs and one beta – all are OK,
and there are no problems, such as installations with metal screws or other
indicators. My Partner DirkVader.de has no problems either.


I ordered an MCX4000 and 36 cfm TMD fan from CrazyPC a while back (I actually asked them to add it to the fan option selection, since it wasn’t). This was before they started to supply rubber washers with the fans, but they did supply it with a 3 to 4 pin adapter as well as the written notice about using non-conductive washers.

I’m using the 3 to 4 pin adapter and fiber washers on the mounting screws (the type that used to ship with MB standoffs) – I’ve had no problem with it and the combination has been working very well on a 2.66 @ 3.1 GHz.


I checked around with some resellers and folks who might know more about this issue. Based on admittedly second-hand information, the overall opinion is that there have been some quality control issues that apparently have been addressed with current products. Making a TMD fan is a difficult engineering task, so early production runs most likely had some quality issues.

If you have a TMD and it’s working OK, don’t sweat it. If there’s going to be a problem, it should show up very quickly.

Email Joe

Clarpet sent in the email:

“I sent an email to YS Tech after hearing in a few forums that the TMD fan issue is still occuring sporadically. Being skeptical about buying one, but still interested, I decided to contact YS Tech and more or less demand an explanation. What I received is below:”

Response from YS Tech:

“Dear Clarpet,

Thank you for your comments! Here I sincerely try to answer and explain you questions and doubts! More importantly, please note that we never insult the intelligence of any people, not only our customers or product users, but also all mankind!

1. Y.S. TECH has never had a recall for T.M.D. FAN. We know Swiftech issued the “worldwide” recall statement by itself and in name of Y.S. TECH. Swiftech is not a customer of Y.S. TECH and never buys anything directly from Y.S. TECH. Y.S. TECH has reserved the right to file the complaint against Swiftech’s plagiarize of Y.S. TECH name!

Complaints to Y.S. TECH T.M.D. FAN can be divided into two types!

2. RPM Monitoring

Yes, there are very few models of motherboards in the market cannot accurately monitor T.M.D. FAN’s tachometer output. However, the RPM monitoring problem also happens to other standard CPU DC cooling fans. However, it is nothing to do with the quantity or defectiveness of a DC fans.

3. Short-Circuit

The fundamental thing here is that every T.M.D. FAN is 100% inspected and is 100% good quality condition while dispatched from the factory. That is, before the T.M.D. FAN is installed onto a heatsink, Y.S. TECH is responsible to its quality and defectiveness. Further, please note that Y.S. TECH does not sells a single T.M.D. FAN to any end users.

However, some of CPU cooler manufacturers or users obtained T.M.D. FAN and installed onto their heatsink with a over-specified force and thus damage the T.M.D. FAN. With an over-specified force applied onto the screws and thus damage the coils at the corners of T.M.D. FAN, it is the wrong-doing of CPU cooler manufacturers and of users when they change the T.M.D. FAN from one heatsink to another.

Marketing Channel:

Y.S. TECH is a manufacturer and sells its CPU cooling fans to CPU cooler manufacturers or agents or distributors and never sells directly to any end users. Y.S. TECH provides services to its customers (CPU cooler manufacturers or agents or distributors) who purchase DC cooling fans directly from Y.S. TECH.

Thus, should you have any product problems, please contact whom you purchase the product from. The sellers (retailers, e-commerce sites, or CPU cooler makers) of T.M.D. FAN should be able and have the obligation to provide you with the services and reminder their customers how to apply a T.M.D. FAN.

I personally appreciate for your comments. Also, I hope I have explained clearly to all issues.

Thank you!

Daniel C. Cheng
Manager / Marketing & Sales Dept.

Y.S. TECH / Yen Sun Technology Corporation
329 Feng Ren Road, Ren Wu Shiang, Kaohsiung, Taiwan ROC (814)
Tel: 886-7-3713588 Ext. 315 Fax: 886-7-3719643 Mobile: 886-932740278
E-mail: [email protected] URL: http://www.ystech.com.tw”


The key quote here:

“With an over-specified force applied onto the screws and thus damage the coils at the corners of T.M.D. FAN…”

It appears that if the metal cover contacts the winding coils at one of the corners, it shorts out – no real suprise here.

The fix is really simple – if you buy a TMD, don’t screw it down so tightly; this is only a fan – it does not generate so much force that you have to use 100 lbs of torque to keep it on. Be aware of the issue, the cause, and take appropriate steps to avoid a problem.

Finally, apparently there are some TMDs sold with plastic covers – seems to me the YS Tech fix is real simple.

I’ve been reading about the problems with these TMD fans, and the various
comments on OC. I am a very experienced engineer (28+ years)and I’ve had
tons of training in failure analysis and failure prevention. I used to run
the quality assurance department for a giant medical equipment
manufacturer–where failure usually resulted in death (really!). My job
now, among other things, is to look for just these types of problems.

I have 2 fans that I looked at. One is model PD1270153B-2F (bought
standalone) and the other is PD1270155B-2F (this is the one that came
mounted to my Swiftech MCX4000). While both of these fans seem to work fine
when plugged into a 12 vdc source, UNMOUNTED, outside on a bench, I can see
exactly what the potential problem might be.

In each corner of the fan assembly there is a coil that sits just below the
metal outer housing. The coil is wound from magnet wire, which normally has
a lacquer coating offering electrical insulation if UNDISTURBED.

Above the
top of the coil windings is an inconsistant amount of a white RTV-like
substance (RTV is like the rubbery stuff you use to caulk bathtubs) — possibly for adhering the fan to the cover and/or offering
electrical insulation. Above that is the inside of the metal cover. One
important thing to note is that the mounting screw hole is plastic lined,
but it’s top is the fan’s metal cover.

Here’s my theory on the failure mode of the entire assembly in a system:

general, if no screws have been installed to hold the fan in place, the
lacquer and RTV between the top of the coils and the cover does an
acceptable job of insulating the cover from the coils. When screws are
installed 2 things happen immediately, and one happens over time–all
leading to the reported problems.

First, the pressure of the screws compressing the metal cover causes the
cover to make greater contact with the top of the coils. As I said above,
the amount of RTV is quite inconsistant. Of the 8 coils I looked at only 2
seemed to be adequately insulated.

This causes a short of the coil to the
metal cover. This alone isn’t enough to cause a problem with the fan. But,
when the fan is mounted with a METAL screw that’s touching the fan cover,
and the cover is shorted to one or more of the coils already, the screw then
shorts this mess to chasis ground.

If the RTV is in fact adequate, a problem can develop over a longer time as
well. Since there’s so little space between the metal fan cover and the
coils, under the best of circumstances there’s very little RTV in there.
More than likely the assembly method is to put a drop of RTV on top of each
coil and then press the metal cover on.

This simply pushes out the RTV and
makes a very thin, precarious layer of RTV and the lacquer on the magnet
wire. Over the course of time the inherant amount of heat generated in the
coils coupled with the pressure of the mounting screw against the cover
causes the cover and coils to come into better contact — and thus a partial
or total short.

My Suggestions for Solutions

Simple, cheesy:

Use plastic screws to mount the fan. (Trying to use metal
screws with plastic washers won’t work since it’ll be very hard to keep the
screw from touching the inside of the screw hole in the fan cover. The
washer will just prevent it from touching the top.)


Remove the metal fan cover and insulate the inside portion of the
corners using electrical tape. Properly insulating the cover from the coils
is the key to eliminating the real cause of the problem. If they haven’t
already done so, YS Tech should consider adding a similar step to their
assembly process, and make the issue go away.

Hope this helps.

Brett Wasserman

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