PSU Compatability

[lpmu81]

I am trying to locate information regarding PSU compatability for an eMachines desktop (I know all of the issues with the eMachines -- I have experienced most of them first-hand ! :) )
The problem is this: I want to replace the 250W Bestec PDU that is in a T2240 desktop. The Bestec PSU actually works fine, but I have read numerous reports about them failing and taking the motherboard with them. I purchased a CooMax 300W replacement PSU that was supposed to be compatible, but it is not. The CoolMax PSU will not power up the unit at all when I install it (I have double-, triple-checked all connections). I'm pretty sure the problem is with the PSU as whenever I put the Bestec PSU back in the unit, it powers up just fine.
One difference I have noticed is that the 20-pin Molex connector for the Bestec units has two additional wires (one pink and one brown). I found a couple of posts on other boards that refer to these as voltage sensors. The CoolMax PSU does not have these wires. I have also seen other posts that say that EMachines uses proprietary wiring while other posts say they do not.
So I'm trying to find out: 1) if it makes sense that these two wires would make a difference as to whether the PSU is compatible with the motherboard in the T2240, and 2) if that is true, where I can find a replacement PSU that is compatible (I was told the CoolMax PSU was compatible when I bought it).
Any suggestions/experiences would be appreciated.

[saphalline]

I have read numerous reports about them failing and taking the motherboard with them.You bet your a$$ they do!! I've seen it so many times that I estimate this happens at a rate of 35-50% after 2 years of use! :eek:

One difference I have noticed is that the 20-pin Molex connector for the Bestec units has two additional wires (one pink and one brown). I found a couple of posts on other boards that refer to these as voltage sensors.Sort of... If you look at the ATX (http://en.wikipedia.org/wiki/Atx) wiring layout, I'm guessing the pink is most likely pin # 9 (+5V standby) and brown is pin # 13 (+3.3V sense). I've seen quite a few modern PSU's leave one or both of these empty because standard off-the-shelf hardware often doesn't use them anymore, especially hardware designed for the ATX 3.x generation. OEM systems, however, use these seemingly useless voltage rails for nefarious deeds, such as forcing you to buy their cr@ppy replacement PSU's at exorbitant prices!

To fix the issue, I suggest you buy a better replacement PSU than a sucky CoolMax one! Far better PSU manufacturers (such as Antec or PC Power & Cooling) make excellent OEM replacements that cater to these more... "esoteric" wiring requirements.