|I took a look at the info for the Dell XPS400 series.|
I had assumed Dell wasn't pulling it's proprietary crap anymore, outside of maybe the PS and case fittings, or custom optical drive fronts, but apparently they still are. This model series at the very least has an oddball mboard, and an oddball PS.
I looked at both the HTML service manual and the PDF owners manual.
It seems it has two fans mounted vertically connected via proprietary cables with oddball end connectors, and the two fan headers on the mboard may be much larger than standard ones.
There is absolutely no info about what the pinouts of the headers are (what each pin is for).
As I said above, some headers for the cpu fan have 4 pins - the fourth pin is for reducing the cpu speed under certain conditions - in that case, if the fan has three wires, on a standard mboard, a standard 3 pin hole female fan connector can sometimes go on in either of 2 positions on the 4 pins - one position works, the other does not.
"One fan I installed a slot fan called a System Blower a exhuast fan that helps pull hot air out of the tower would'nt you know it has a four pin connection"
Sounds like that was meant to be plugged into a standard 4 pin cpu fan header that some recent mboards have.
3 in a row of the 4 wires are wired exactly the same as for 3 wire fans. That should work fine with the Easywatch 3 pin connector if you plug into the right 3 pin holes in a row.
There is insufficient info in these manuals, so I cannot tell you how to hook up the oddball end connectors from the fans, and I cannot tell you if the fan cables have their wires in the standard pattern or not. The only thing I can suggest is for you to look on the mboard near the headers to see if there is labelling next to the pins - e.g. + and - for power, r? or something else for rpm.
The 3 male pins on each connector from the EasyWatch are probably arranged and wired in the standard pattern, and they fit onto a standard female connector for a 3 wire fan only one way - the pin holes are closer to one side.
power + polarity is in the middle, the wire color might be red; power - polarity (power ground, also serves as rpm ground) is on one end, the wire color might be black; rpm is on the other end, the wire color might be yellow, or some other color not black or red.
If you can't confirm what pin on the mboard header is for what, or what wire from the fans is for what, you risk damaging something if you splice the wires from the fans to the EasyWatch.
You can get standard 3 position female connectors (the holes are spaced at 1/10" , .10", intervals) from places that have electronic part and install them on the fan wires yourself, but you have to be able to determine what each wire is for.
AND as I said previously, the cpu fan MUST be connected to the mboard header.
On second thought using a Y wiring arrangement to connect the cpu fan to both the EasyWatch and the mboard header could also damage the mboard circuits and the Easy Watch circuits - two pins on the EasyWatch male 3 pin connectors are powered from the EasyWatch wiring AND two pins on the header are powered - connecting the Y wiring may cause a short! (although sometimes you don't have that problem with low voltage DC circuits)
If you don't want to take the risk of messing with any of that, you may be able to install a standard case fan inside the case somewhere and monitor that with the EasyWatch.
The EasyWatch would hook up fine if the system had a standard mboard with standard fan headers and the system had standard fan connectors from the fans (they've been the same since at least the mid 90's). You take the chance you're going to run into this proprietary crap when you buy a Dell system.
As far as I know, other brand name systems do not have this problem, except possibly for models that have special server mboards. At least, HP and Compaq have not used other than standard mboards for a long, long time.
Most brand name system builders DO NOT make the mboards in their models - they are supplied to them by major mboard manufacturers.
Look on the mboard for an obvious model number printed on it in larger characters, often between the slots or near the center of the mboard. If you find that there may be other places where the pinouts for the fan headers can be looked up, etc. On the other hand, this oddball mboard may not have that.