Matrix Orbital Corp

Posted: **Wed Oct 15, 2003 9:17 am**

I have a new MX212 rev 1.4. The fans are pulsating when using the Advanced GPO to control them. I have four case fans (0.15ma) connected to two Advanced GPOs. I can see the fan LED intensity pulsing about once per second, with a larger pulse every third second. You can also hear the variation in the fan speed. This pulsating happens with the display started or when in

Posted: **Wed Oct 15, 2003 3:17 pm**

Hello...

Through this whole procedure does the display act "differently"...? By differently, I mean, does it reset...?

What type of fans are you using...? This is usually a symptom of smaller fans when RPM sensing and PWM are both on...?

Posted: **Wed Oct 15, 2003 3:35 pm**

No, except for the pulsating of the fans and the flicker of the LCD display, everything else seems to operative normally.

Posted: **Wed Oct 15, 2003 4:19 pm**

This is a side effect of monitoring RPM. PWM to the fans and RPM sensing at the same time is difficult. If you turn off the RPM sensing it should stop that effect. This tends to be more pronounced with smaller or slower fans.

Posted: **Wed Oct 15, 2003 4:19 pm**

I have:

Four Cooler Master 80mm case fans (0.15A)
http://www.coolermaster.com/index.php?L ... e=+TLF-R82+

One Zalman CNPS7000A-AlCu CPU Cooler (not sure of the current but it sould be less than 1A, 92mm fan at 2400 RPM)
http://www.zalman.co.kr/english/product ... a-alcu.htm

One 80mm card cooling fan (0.25A)
http://www.zalman.co.kr/english/product/cnpsvga3.htm

Currently I have four case fans controled by two GPOs (two each).

The other configuration I tried is with the four case fans on one GPO (0.6A) and the CPU and card cooler fans on the other two GPOs.

Posted: **Wed Oct 15, 2003 4:23 pm**

I will try turning off the RPM sensing. I am at work now so I will have to wait until I get home.

Posted: **Thu Oct 16, 2003 8:53 am**

Yes, turning off RPM sensing solved my problem with the fans pulsating. Everything is working just fine now. Thanks for your help.

Posted: **Thu Oct 16, 2003 9:09 am**

I'm glad that you got everything resolved...ENJOY!!!

Posted: **Fri Oct 17, 2003 12:45 pm**

I notice the following statement in the LK202-24-USB Rev 1.4 manual.

"NOTE It is not recommended that the RPM is checked more than once every two seconds. If the RPM is checked more frequently, the actual RPM readings can become very erratic."

Was my problem with the pulsating fans caused by the frequency that LCDC checked fan RPM when the RPM sensing was enabled? In other words, if there was a change to LCDC so that it could be configured to check the fan RPM less frequently, would that work without causing the fan pulsating problem?

Posted: **Fri Oct 17, 2003 1:04 pm**

The reccomendation to check no more than ever two seconds is just for that reason. Any more can cause the fans to pulse but moreso, it will cause the fans to speed up. We're working ways to improve this, but like I said, PWM and RPM sensing at the same time is difficult. I actually don't know of any other product that will do RPM sensing and PWM speed control at the same time.

Anyway, as for LCDC, I don't know. I think we would have to get Matt in on this conversation to figure that one out.

Posted: **Fri Oct 17, 2003 1:31 pm**

My motherboard (Intel D875PBZ) implements both RPM sensing and PWM speed control. I don't know how well it works because I only enabled it once for the CPU fan. The BIOS did not implement control of the target temperature and the CPU fan speed would increase at a higher CPU temperature than I liked. The MX212 is turning out to be a great solution where I have much more control. A forth Advanced GPO would be nice, but you cannot have everything.