If you have a Dell DA-2 power supply I know exactly what your problem is...and the solution is not perfect...but way too easy. Turn the damn plug upside down and just CRAM IT IN!! I know the pins don't match...BUT JUST PUSH REAL HARD!! It will go in.
I know what you're thinking..that guy is an idiot. Well just finish reading this post and you'll say that guy is a f'n genius
OK now...If you have the DA-2 which I highly suspect that you do, don't fault performancepcs. They sent you exactly what you ordered. The problem is with Dell. They reversed the top and bottom row of the 8pin molex connector. DAMN THOSE BASTARDS!!
After entirely too much research (probably 2 days) I found out the DA-2 has some kind of a safety circuit in it, and if it is not shorted to one of the ground wires the power brick will not turn on. The brick has an LED and if you plug in the P.S. the LED will turn amber. If you plug 8pin end into the correct device the LED will turn green. If you plug it into a device with the wrong polarity the LED will turn off...which will actually save your computer if you get it wrong. I know, it saved mine. Whew!
Anyway, this is how I figured it out.
I used a plastic coated paper clip as a jumper to test the pins in the DA-2. The safety circuit is on the top left with the clip facing up....err at least I'm 90% sure it's up. Sorry, but I'm not going to unplug my computer to make sure. Just jump the top left pin and the 2nd, 3rd or 4th pin next to it and you have verified these as the ground (black) wires. Now all you have to do is mate these wires with the black wires on your computer and the bottom row with the white wires on your computer and you're done. TOOOO EEEEEASY!!! Too bad
Dell had to confuse everybody by getting some non-standard 8pin molex connector.
Believe it or not, I ordered the exact same 8pin to 4pin connector that you did from performancepcs non the less. Only I didn't look at the patterns when I ordered it. I just thought it was a tight fit and crammed it in there. I'm used to that.
Oops! I was like HOLY CRAP!! The amber LED turned off on my brick and I thought I lost a $40 P.S. Luckily it reset when I unplugged it. Whew!
Bottom line: Just turn the connectors with the clips in the opposite direction and force it in there. It worked for me.
I hope it's not too late to help you...and if it is I at least hope it helps somebody else. I know this is a very common problem.
Case: Lian Li PC-Q07
Power Supply: Dell DA-2 & PicoPsu-160-XT
Processor: i5-760 (OC'd EasyTune6 3.36 Ghz)
Motherboard: Gigabyte GA-H55N-USB3
Video Card: Gigabyte ATI Radeon 5570
SSD: Crucial 128 Gb
Memory: G. Skill 8gb (2x4gb) DDR3 1333 (PC3 10666)
OS: Windows 7 Pro
Heat Sink: Noctua NH-U12P (1 fan)
DVD Rom: Full SizeEdited by Moocher - 9/26/10 at 10:52pm