Solved One Fan Not Running On Startup

[Whisperss]

So I recently had an issue where my ROG G75VW crashed due to an overheating GPU (see thread under BSOD Help and Support, thread title: BSOD... yet not). While physically cleaning the machine, I decided to start it up while the back was off to observe fan function. FYI the laptop was cold, having sat for 12+ hours. I fired up the laptop under battery power and observed that of the two fans, the fan farthest from the the power port did not start. One of three things comes to mind:

1) Due to the laptop being cold, only one fan started
2) Because I was using battery power (and it was cold) only one fan started
3) I have a dead fan

Searching the net didn't find me anything, perhaps I was using the wrong search terms. At any rate, I emailed ASUS just now and am waiting on a reply but I thought I'd ask here and get you guys' opinions. I'd rather not pay for a diagnostic bill if I can avoid it so thanks in advance for your help.

 

[Megahertz07]

To save power and to be quiet, most laptops only run the fan when the CPU is very hot.
Never seen a laptop with two fans. One is certainly the CPU fan. The other can be a case fan or GPU fan.
Can you identify what is the fan that isn't running?
Did you search for a service manual?

 

[Whisperss]

Yeah it's a beast of a machine, especially being 5+ years old. Dunno if it's typical of all ROG laptops but it has two massive exhaust ports out the back and is probably half again as thick as a standard laptop, if not more. It's more of a desktop replacement than a true laptop, especially considering it weighs nearly 10lbs including the power cord and has a whopping 3.5 hours of battery life if you are NOT gaming, lol. I'll see what I can find for a service manual, didn't think of that.

UPDATE: Well it took an ungodly amount of research to figure it out but yes, the one that started up is for the CPU and the other is for the GPU. Even searching for service manuals got me a lot of info on disassembly but only one site bothered to mention which was which. Guess that answers my question though, thanks.

 

[Megahertz07]

Do you have a hardware monitor? I use this Open Hardware Monitor - Core temp, fan speed and voltages in a free software gadget
Set to show one core at task bar.
Set it to start with windows.

 

[Whisperss]

Downloaded it, laptop has been running for a couple of hours under regular usage (no gaming). All four CPU cores are running about 4% usage and 120 degrees F. GPU core running at 102 degrees and barely any usage (jumps to 4% but sits near 0%). HDD shows 102.2 degrees F. Don't see the fans listed but I also don't see anything to be concerned about. The CPU is a touch warmer than I'd like but they certainly aren't reaching critical temps by any means.

 

[Megahertz07]

50ºC (120ºF) is low for laptops.
I have seen laptops running above 90ºC (195ºF)
You have to worry when it goes above 80ºC (176ºF)
On laptops the fans will only run on high temperatures.

 

[Whisperss]

Well, I'm calling it good then. Thanks for your help.