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Flea0
10-08-2013, 01:59 PM
after undervolting the CPU the left-hand fan is barely audible while the GPU one idles at higher rpm.
I was hoping to make the laptop nearly silent for activities such as browsing. Currently, the GPU idles at 42-43C with the fan on low all the time. It's still almost whisper quiet, but I was wondering if there was a way to get the fan to slow down even more.

Considering that fan rpm control software doesn't work on the G750, does anyone have any hints?

iweber95
10-08-2013, 05:18 PM
no idea, g750 is already so quiet u cant ever hear the fans!

adamsyes
10-08-2013, 05:37 PM
that would be up to the OS. believe it or not. im currently on windows 8

GPU Fan is never on. unless I start a game

gpu temps idle are 40-45c

before, when I installed windows 7. my gpu fan would be constantly going on and off

hmscott
10-08-2013, 06:31 PM
after undervolting the CPU the left-hand fan is barely audible while the GPU one idles at higher rpm.
I was hoping to make the laptop nearly silent for activities such as browsing. Currently, the GPU idles at 42-43C with the fan on low all the time. It's still almost whisper quiet, but I was wondering if there was a way to get the fan to slow down even more.
Considering that fan rpm control software doesn't work on the G750, does anyone have any hints?

I wouldn't recommend slowing down the fan. It is running at the optimal speed that the sensors determine is needed to keep the laptop cool. The G750JX is already delaying ramping up the fan, favoring quiet over a cold CPU

I can't hear the fan at idle on my JX. I have it sitting on a non-reflective surface, and there are no obstructions behind the laptop to reflect the sound. You could work on removing sound reflecting objects, or putting a sound baffle in between the fan vents and the sound reflecting object. Placing the laptop on a square of carpet that extends a bit out from the back to catch sound and absorb it is a trick I have used in the past in acoustically active rooms.

But, to directly answer your question, you could put a resister in line between the fan and the power supply. Typically it is a variable resister, but manufacturers also supply inline fixed value resisters like this:

http://www.endpcnoise.com/cgi-bin/e/rc56.html
http://www.quietpcusa.com/Fan-Resistor-Cables.aspx

I haven't traced out the fan power cables, but you would likely need to splice in a resistor by hand, as all the cables I have seen have tiny connectors - finding a pre-made cable might be difficult.

Even tougher would be finding a small enough rheostat to fit in the laptop / through the case so you could adjust it. Here is a simple DIY for a standard case rheostat add in, to give you an idea of what it takes to splice into the power cable.

http://www.bit-tech.net/modding/2001/12/10/adding_fan_speed_control/1

And, finally, editing the DSDT may allow for setting the fan speed transitions. I don't recommend doing this as it is fraught with peril, but here is a pointer to various discussions on DSDT:

https://www.google.com/search?q=DSDT+%E2%80%93+Differentiated+System+Desc ription+Table

And, one old article on specific steps to alter the DSDT settings to change the fan settings in HP laptops:
http://notebookequus.blogspot.com/2008/09/patching-dsdt-table.html

Again, there are definitely laptops/desktops I would vote for finding fixes for fan noise, but the G750JX isn't one of them.

Except for the annoying fan up / down activity near idle for the JHA :)

BTW, how much are you undervolting your CPU/cache? I have my JX set to -65Mv now, a big temp drop from -50Mv, and my JW used to work fine at -100Mv. If you haven't pushed the envelope in dropping the voltage to a certain crash, you might get more temperature drop by dropping the offset voltage further.

Flea0
10-08-2013, 08:31 PM
I'm ruling out any solution that requires soldering, I was mostly thinking of ways to make the GPU draw less power and thus idle at a lower temp, but as we know undervolting or underclocking it are severely limited. my JX works fine at -100mV on the CPU.

hmscott
10-08-2013, 11:49 PM
I'm ruling out any solution that requires soldering, I was mostly thinking of ways to make the GPU draw less power and thus idle at a lower temp, but as we know undervolting or underclocking it are severely limited. my JX works fine at -100mV on the CPU.

Cool, glad to hear you got a tolerant CPU. As a heads up, I set up my JX with -100Mv like my JW when I first got it, and didn't realize it was the reason my laptop was resetting when running BIONC/FAH - I initially thought it was GPU related overclocking. You might find something sensitive to the -100Mv under volt at some point as well.

The voltage control on the Asus GPU Tweak tool doesn't seem to do anything. I am assuming it will take a new app using the API unique to the G750 GPU's, or a custom flashed vBIOS.

So the only option would be editing the ACPI DSDT table, but that would take some sleuthing to get it to work correctly - without help from Asus.

Flea0
10-08-2013, 11:55 PM
yeah I don't perform CPU-intensive tasks such as BOINC or video encoding often, so I'm not pushing the limits of stability.