Post by: hand_of_LAW on November 20, 2003, 10:58:00 PM
Does xbtool still change the speeds now ?.
Has anyone slowed down the 12v modded fan to a more tolerable speed/noise rating, ie wots a good compromise ?
thanx...
Post by: Exobex on November 21, 2003, 07:45:00 AM
Post by: chelrob on November 21, 2003, 05:19:00 PM
Post by: Sykotek on December 05, 2003, 06:26:00 AM
Post by: chinmi on December 05, 2003, 08:07:00 AM
| QUOTE (Sykotek @ Dec 5 2003, 10:25 PM) |
| What would happen if I set the fan speed in my bios to something over 100%? Didn't want to risk a frag but I was wondering..... Thanks! |
if you do a hardware mod by connecing the black fan wire to the ground connector on the motherboard (not on the fan connector) the fan will run at 12v, this is because the ground motherboard have a permanent 0 voltage power...
the original black wire fan connector have a default 5v power... so the fan will run at 7v by default (12v red wire - 5v black wire). the original black wire fan connector is the one that have a variable voltage ranging from 5v to 0v which make the fan run from 7v to 12v.
since the hardware mod makes the black wire fan cable is not connected to the original black wire fan connector, any software mod (like unleashX) or bios mod (via xbtools) that alter the voltage of the original black wire fan connector will have zero effect on the fan....
so...
is it save if you do a hardware mod and then accidentally do a software mod/bios mod ??? the answer is yes
does a software mod/bios mod applied to a hardware mod fan have any effect on fan speed ??? the answer is no
is it save if you do a software mod/bios mod and then accidentally do a bios mod/software mod ??? i don't know the answer yet
any one have the answer ???
Post by: Exobex on December 15, 2003, 08:07:00 AM
| QUOTE (hard jokur @ Dec 5 2003, 08:13 PM) | ||
the 12V mod does not work that good... I compared the 2 on board fan headers and the GPU one put out more power at the same voltage. I tested bot connects with a DVM and both read 11.8v Now either the case fan connect is really "pulsed" like I read on a different thread or it's just not putin out the current like the GPU header does. Rich |
It's likely to be pulsed. Running it at a variable voltage (through a transistor, for example) is likely to cause that transistor to heat up.
PWM (Pulse Width Modulation) will run it cooler, because:-
When fully on, the transistor will have very low resistance (therefore pass a lot of current), but the voltage across it is only going to be about 0.6 volts, so very little needs to be dissipated as heat.
When fully off, the transistor will have very high resistance (therefore passing VERY little current), even though the voltage across it is near 12 volts (the motor effectively forms part of a potential divider, its relatively low resistance means the voltage at the connection between it and the transistor is closer to 12 volts - anyway...) the very small current means that once again, very little needs to be dissipated as heat.
Example: 12 volt, 1 amp motor (12 watts), run through a transistor:-
1) Transistor fully on: motor runs at 11.4V, near-as-damnit 1A.
Transistor dissipates 0.6V x 1A = 0.6 watts of heat
2) Transistor half-on: motor runs at 6V, therefore at 0.5A.
Transistor dissipates 6V x 0.5A = 3 watts of heat
3) Transistor fully off: motor runs at 0V, 0A.
Transistor dissipates 12V x 0A = 0 watts of heat
In other words, it's better to be fully on or fully off than half-way there. If the transistor is switched on, off, on, off, on, off instead, the fan will still run at half-speed, but the transistor stays cool and you've reduced heat emission by 2.7 watts.
By adjusting the "on" time relative to the "off" time, you vary the motor speed. This is also how most lighting dimmer switches work (unless you're using a variac - a big transformer with a voltage knob - for the job).
