2-pin graphics card fan to 3-pin fan controller?

Angilion · 31 Jan 2006 at 22:14

I have a 7800GT with the fan stuck at 100%, which is horribly noisy. I don't want to RMA it, because the company is known to send out 2nd-hand replacement cards and there are numerous reports of the cards being flakey anyway. The one I have works fine, so I'll stay with it.

So, I want to slow the damned fan down. The heatsink on the fan is very good (solid copper) and of course the fan is more than adequate at half speed. All I need is a way to turn it down.

I have a fan controller that will control 3 fans and I only have 2 on it, so connecting the graphics card fan to it would be convenient.

Is this possible?

The fan power header on the graphics card is a 2-pin one and the fan has the usual two wires, red and black. Female connector on the end of the cable from the header to the fan.

The connector to the fan controller is a 3-pin male connector, but only two pins exist, connected to two wires, red and black. Presumably it was made that way to conveniently accept the more common 3-pin connectors from a fan.

Is it as simple as disconnecting the graphics card fan power cable from the graphics card and connecting it to the fan controller cable? If so, where can I get a convertor from 2-pin female to 3-pin female? The guage of the wiring is different (the wires from the graphics card fan are much thinner than the wires to the fan controller), but I'm fairly sure that isn't an issue - the fan would only draw the current it needs, right?

Would the graphics card detect the lack of a fan connected to its power header?

If so, I'm thinking that a Fanmate2 would do the job, but that's also 3-pin so I would need a convertor.

Finally, how do I find the startup voltage of the fan on the graphics card?

I know that I could avoid the issue by fitting a Zalman graphics card cooler, but I'm interested to see if this works and I'd prefer to wait for the VF900Cu.

Angilion · 1 Feb 2006 at 00:11

sagaboy2 said:
riva tuner will let you slow the fan down.

Not on these cards. The author of RivaTuner has confirmed that. Nor do any other fan control programs, for the same reason.

Angilion · 1 Feb 2006 at 17:23

Bumpity-bump...I'm after a 2-pin to 3-pin convertor and a more definite "yes, you can do it that way" or "no way, man, that will crash and burn!".

Angilion · 1 Feb 2006 at 18:11

It's also possible to control fan speed by varying the voltage to it, so the yellow wire you rightly describe isn't always needed. As I said, my fan speed controller uses only two wires, red and black.

This does touch on an issue, though...where is the voltage regulation for the fan on on XFX 7800GT Extreme Noise Edition cards? It appears that the fan power header always supplies 12V because the LEDs on the card are powered from it too. I haven't checked that myself, but other people have.

Angilion · 2 Feb 2006 at 00:29

Pegasus...would you mind taking a look at the wiring to the stock fan and the LEDs for your card, if you have the version with LEDs? You should have a nice clear view with the plastic cover off.

If so, is it true that the same wires from the power header on the card are routed to the LEDs and the fan, just split off partway along? I have seen that reported, but I haven't messed with the card yet to confirm it. If that's true, it looks as though the LED edition doesn't actually have fan control - the LEDs always have 12V supplied to them.

Pegasus and Fx-Overlord: I don't recall seeing GPU temp or GPU fan speeds with Speedfan, only CPU temp and fan speed, plus two case temps and HDD temp. I don't have it running any more (during one of my many attempts to get fan speed working on my graphics card, I removed Speedfan from the autoload list and I haven't put it back).

Angilion · 2 Feb 2006 at 22:46

The card does lack PWM, which is why RivaTuner can't control it (according to the author of RivaTuner).

As yet, I have not seen any evidence that the XFX 7800GT Extreme Noise LED Edition has any fan speed control at all on the UDE* models. The UDF3 and UDF7 models definitely do have it, but it's uncertain about the UDE3, UDE7 and UDER models. I find it hard to believe that XFX would screw up so badly, but there's no sign of fan control on the card and no reports of a UDE* model with working fan speed control.

Which is why I asked Pegasus to take a look, as their card no longer has the plastic cover on. Reports are that the fan and the LEDs are power from the same wires. The LEDs require 12V. This is reported confirmed by using a Fanmate to change the output from the power header on the card to 5V - the LEDs go very dim.

So if there isn't any PWM and the fan is powered from the same power header and on the same wires as the LEDs and the LEDs require 12V...where is the fan speed control?

Angilion · 4 Feb 2006 at 20:50

Hmm...my CPU temps only rise 9C when gaming, so not much scope there. Apart from the graphics card, I'm pleased with my cooling. Of course, I will still be trying to get it quieter once I sort out the graphics card cooler. You know how it is once you start working on PC noise.

I've given up on XFX fixing with issue, but I am interested in knowing if the card has any facility for fan speed control at all. The first possible claim of a UDE* model XFX 7800GT Extreme LED Edition with working fan control went up on XFX's forums last night, but the person wasn't sure that it wasn't fan speed variation on their CPU cooler changing the noise levels, rather than the graphics card.