Question : Problem: Confused about power supplies, 20 pin, 20+4, 24 pin?

Hi everybody,

I have been removed from hardware support for some time now and need some help as I seem to have gotten a bit rusty.  I have to replace a power supply on a Compaq Presario Desktop, system number PP158AA.  I looked at several different PSU's but got confused so I came here.  On the mobo, (K8S-LA), the main connector is a 20 pin, with the 4 pin connector for the CPU.  Here is a link to the hp site with the mobo specs

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00257657&lc=en&cc=us&dlc=en&product=443737&lang=en

What would be an acceptable PSU replacement?  If I buy a 20+4, do I use the +4 for the CPU connection?  Do I need to use it?  Can I just not plug the +4 in?  What is the difference?  Is there a good guide out there or is it just experience?  It really bothers me that I don't know this.  There is not much running in this case, 2gb ram, hd, cd and that is it.  I did a search for the part number, HP-D2537F3R, and found some that claim to be exact replacements, but I don't want to buy the wrong thing and have to return it.  Also, I like to do my shopping at newegg and hesitate to go elsewhere due to being burned in the past.  Thanks for any help you can offer.

Answer : Problem: Confused about power supplies, 20 pin, 20+4, 24 pin?

Any acceptable PSU replacement has the 20 pins connector.Don´t  try to use the +4 pins connector or any 24 pins PSU. The 4 pin connector for the CPU is a 12 volts power connector used to provide power to the cpu. it is mandatory in order to drive the proper amount of current to the CPU without the risk of damage to the MoBo due to the excesive current crossing the thin lines from the 20 pins connector. the PSU with 24 pins (or 20 + 4) connector use this 4 pins (11,12,23 and 24)to handle +5v and +12v.   With the exact replacement you don´t need to take care of similar connectors. With Compaq PSU you use the spare part number ( in the form XXXXXX-XXX) in order to get this exact replacement with any good provider.