Fans "throttling" and num-lock light staying on after shutdown

[Adhoc]

PSU: Corsair TX650W
mobo: asus m4a78t-e
Nvidia gtx 260
phenom II x3 720 (cooled by xigmatek dark knight)
Antec 300
ocz ddr3 4gb 1600

When I turn my system on, the front fan and LED along with all the other fans seem to "throttle", as in cycle high and low, and the LED's get dimmer and brighter too.

Then, after I turn my computer off, the num-lock light on the keyboard stays lit until standby power is shut off.

Any suggestions why these events are happening?

Thanks

 

[jmdixon85]

Is your system still running ok? Sounds like a big fluctuation on one of your PSU rails. How are the fans and lights connected, into the same molex with pass-through's or a seperate molex on the PSU cable?

 

[Adhoc]

the back two fans are connected through a single pass through.

Though the front fan, the one that i can see the LED's fluctuating, is connected to a mobo header

the other front fan shares a seperate molex on a line with the dvd-drive

 

[CharlieCS]

If the fans are hooked to the mobo they will go full power until PWM kicks in , graphics card fan will act the same way as well . About numlock led i have no clue am not even sure if mine stays off or on lol

 

[Adhoc]

does that explain the LED's on the front fan getting light, then dim, then light again though?

and anyone have suggestions about the num-lock key?

(btw, the system itself runs fine as far as i can tell

 

[jmdixon85]

Yes the LED's on the fan would dim as the fan slows down. My numlock also stays on when my PC is in standby. Hell, even my LED mousepad stays lit!

 

[hokiealumnus]

Your KB LED will stay on when shut down because of the stand-by / suspend features on most modern systems. It's ready for input, even if the power is turned off. You can try turning off those features in BIOS, but chances are the LED will remain on. It's likely just a function of being easier to leave standby power to the KB than to try introduce BIOS code to make it selectable.

As far as your fan, most likely your BIOS fan control is enabled. At startup, it sends full power to it. When it reaches that point in the POST process and detects temperatures in the lower range, it reduces the voltage to your case fan (which in turn dims the LEDs).

 

[Adhoc]

thanks all

so would my fan being an antec tri-cool explain why it dims, yet then goes back to full?

 

[hokiealumnus]

No, having the voltage reduced to the fan would explain why it dims, then goes back to full brightness when its speed increases. It would happen with any voltage-controlled LED case fan.

Unless I'm misunderstanding and it goes to full brightness while the fan stays at a reduced speed?

 

[Adhoc]

well the fan cycles from high to low to high in the span of about 3 secs. but i guess it's normal

 

[hokiealumnus]

In that case, the LED fluctuating with fan speed is perfectly normal. If it's happening before the OS loads, it's a setting in BIOS. Check for something called "PC Health" or similar and turn off BIOS fan control. See if that stops the odd behavior.