I have an Alienware Aurora R2 and I trying to change the power supply. The one that it came with "Model DP/N 0U597G" do not work anymore so I have purchase an 875W power supply - Model DP/N 0J556T.
Compatible Part Numbers: W299G J556T U595G NPS-875BB A N875EF-00 H875EF-00 - According http://www.ascendtech.us/dell-j556t-875w-power-supply_i_csdelj556t875wt.aspx the 0J556T should work with the current cable that I have now, but it did not. The pin configuration are different as you will see in the pictures below.
I would like to know if it should work or should I buy the same 525W DP/N 0U597G model power supply.
The one that I bought:
The one that came with the computer
The plug for my computer
The plug for that came with the 875W Power supply
The cord for the 875W is also to short
My computer Aurora R2 2404
You could remove the 24pin cable ( white connector in your pic with P1 stamped on the side ) from your old PSU cable harness and install it to the new one. You have to trace each wire from the old one and then pop them out of the power connector that plugs into the PSU. If the color coding is the same then it should be pretty easy to do. A local PC shop could also do it for you.
Another option is buying the correct harness. It is clear that the one that came with your new PSU was not made for your Alienware since it much shorter then it should be.
Last option would of course be returning the one you bought and buying one directly from Dell. Aftermarket PSUs also work but you need to make sure that whatever you buy will actually fit in the space made for the PSU.