I recently replaced my EX495 fans with a pair of GELID Silent 8 PWM fans because I thought one of the stock fans was making a bit of a screeching sound. Don't know whether these are ok fans or not really.. Turned out I think to be the Power supply fan so I'll be trying the "Oiling fix mentioned in the wiki"...

Well, after installing these, I noticed that instead of them running at a nice steady 1200rpm like the stock fans, these were running around 880-930 rpm and my CPU Temp was up in the 46-51C range. The Temp seems a bit high for a lightly loaded dual core system and the fan speeds were slower than I expected. These fans are rated for 900-2000rpm and perhaps the stock ones were a 3k RPM fans, so that would probably require some bios adjustments.

I had previously added the wonderful Video cable adapter, so I figured I'd just change the BIOS settings and increase the fan speed some. Try as I might, every time I started it up, the fans were running back at the same speed again.. Huh?

SOLUTION: On the HP tab in the BIOS settings, you can set the fans to ramp up to some other speed for 5 seconds during startup. I did this to prove that the fans were working properly. However, there's also an option on this tab to disable automatic fan speed settings. With this enabled, it will reset the PECI settings (probably) based on your CPU each time the machine restarts. So, you have to disable this in order to tweak the fan settings in PECI.

In PECI Zone 3 BIOS settings, I decreased the min temp where the fans would start increasing from the stock 56c down to 41c
I also decreased the upper end where the system should force the fans on high from 77c down to 59c.

Now the fans run around 900-950 with cpu settling @~40-43c

Highly recommend the video cable as it made all this quite managable except that I have to pop the top to get at it whenever I want to connect a video cable. That's my compromise for not hacking the case too much as I've already removed the black screen off the back (because it collects too much dust and blocks airflow). I've also clipped the metal mesh away from around all 3 fans to further reduce back pressure. Next time I'm in there I'll snap some BIOS pics.

Wow I was just posting a reply on another old topic on the subject.
What is different in my situation is my cpu temp is somewhat fine. It is my system drive that gets a little warm.
Due to I have a quad core cpu now and I changed my system drive to a wd black.
So my goal is to force the fan speeds up a tad to help lower the temp on drive bay 0
Is there any way you could post some images soon on the bios settings in question?

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Ok, here are some BIOS Screen shots of my EX495 related to the Fan control. Hopefully I did the image uploads correctly and that someone finds them useful.

Note that contrary to two of the screen shots below, I do have the "H/W Health Function" [Enabled].

First shot just shows the main bios screen with what hardware I'm running. Note I have upgraded to 4gb Muskin PC2-6400 memory. Ordered directly from Muskin.


The HP menu has a couple of interesting settings. The first is where you can change the Initial speed the fans are run at for the first 5 seconds. I set these to 100% to blow a little dust out of the fans and stretch their legs a bit on startup. The second is where you need to disable the "override fan speed settings" option. Otherwise it simply restores the settings that it things you need based on the CPU installed.


Here is the Advanced BIOS menu and I've hilighted where we find the Fan control settings.


In the Fan Control (Hardware Health Config) menu, I show the settings I'm currently using. Note that My new GELID fans seem to be enough different that they do not spin the same speed with the same settings. So, I put the normally faster fan on the bottom closer to the system drive which runs much hotter than my WDC Green 2TB EVDS drives.


Here is where I changed the upper limit temp above which the system forces fans on max. IGNORE that this shot shows HW Health Disabled... Forgot to snap the pic with this enabled.


Here's the shot where I altered the lower limit. Above this threshold, the system starts to ramp up the fan speeds.


I did not tinker much with the slope of the fan speed curve. I believe this determines.. for a given change in temp, how much the fan speed will increase... So, in this form, you could also change the Fan controls so that INSTEAD of "Auto - PECI", you could choose the "Zone 2 & Zone 3" setting. This would then allow you to have one fan controlled by the Internal SIO temp and the other fan controlled by the PECI temp. I didn't investigate what the SIO temp is all about. Maybe I'll investigate...

Thank you, it is a little more complicated that I thought.
I understand PWM
What is meant by the zones 1-3.
Backplane
Internal SIO
PECI

_________________
VGA/PS2 Keyboard/PS2 Mouse/Serial debug board
Popcorn C-200
Popcorn A-200
Dune HD Connect
Rasberry PI OSMC(KODI)
ReadyNAS RN316
Amazon FireStick
Amazon ECHO
AnyDvD
MyMovies

It isn't that complicated really. The "zones" are just the different temp sensors. The backplane (zone 1) where the drives plug in doesn't have a temp sensor, so that leaves the processor PECI temp (zone 3) and the SIO (zone 2) temp sensors to choose from. Don't know what the SIO is yet.

I think You can choose to have both fans controlled by the processor temp or have their speeds controlled by different temp sensors.