When the power light is not Green it indicates a bad Power Supply.The Power Supply in your computer is an ATX model.ATX is the Form Factor.The ATX form factor for a Power Supply is;1) The case measures approximately 6 inches Wide, 5-1/2 inches Long, and 3-1/2 inches Tall.The power cables also detail the ATX form factor,
http://en.wikipedia.org/wiki/Power_supply_unit_%28computer%29Scroll to the bottom of the page, and look at the chart to the right;24-pin ATX12V 2.x power supply connector.[ Your Power Supply is also a SMPS.Switched-Mode Power Supply,
http://en.wikipedia.org/wiki/Switched-mode_power_supply ]The maximum rated Wattage is 300 Watts.Primer:A) IF, all of the LED light were on at once, they would use less than 1 Watt of power.B) EACH fan uses 2 to 3 Watts of power.3) A typical Processor can use from 51 to 125 Watts of power.Your power supply doesn't even have the power to spin fans, much less turn the Processor on.Bad power supply.This is an example of a decent, reliable ATX power supply replacement,
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4844034&CatId=4324Replacing the Power Supply;This is HP Support > Compaq Presario SR5110NX Desktop PC > Manuals page,
http://h10025.www1.hp.com/ewfrf/wc/manualCategory?cc=us&dlc=en&lang=en&lc=en&product=3436819&Left-click on the top file listed in blue - Upgrading and Servicing GuideNOTE*This is a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.It may take up to 30 seconds before the first page comes up.Shows you how to open the computer case. (Removing the side panel)This details out replacing the Power Supply,
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01355925&tmp_task=useCategory&cc=us&dlc=en&lang=en&lc=en&product=3436819NOTE*The plastic front of your computer is the Front Panel.The area of pins on the motherboard, that the wires from the Front Panel go to, is the Front Panel header.When replacing a Power Supply it is easy to accidentally disconnect one, or more of these wires. I do not know if a pinout chart for the Front Panel header is available.I suggest you use a good light, and your cell phone, or digital camera, to take a few photos of the connections, of the wires going to the Front Panel header.If a wire or two is disconnected, you have photos.Also:1) UNPLUG the computer from power before you start.Follow Anti-Static Precautions.Anti-Static Precautions:Your body carries Static electricity. Static WILL fry out (Short Circuit) the delicate hardware components inside a computer. (Laptop or Desktop)Computer on a table, computer unplugged from power, computer case open.TOUCH an unpainted surface, of the metal frame of the open computer case.This simple action will relieve your body of Static.Should you leave your computer in the middle of working on it, be SURE to Touch the metal frame again upon your return.IF, you have ANY questions as to where the various power cables go, or an associated question regarding Power Supply replacement, please state in a Comment.Regards,joecoolvette[ You press the Power On button. The first chipset to receive power is the BIOS chipset.{ Basic Input/Output System}The BIOS program is initialized.BIOS looks to see what devices are connected, does a Ram Memory count, turns the Processor on, then hands the computer over to the Operating System.Windows XP and Windows 7 are two examples of an O/S.Operating System ]
