hello help, yes i have a computer that will not power up. i had trouble turning this computer(hp6740c) on before. i am first going to test the plug, also i have a red button on the back near the power supply that is switched either up or down( not sure what this is.) my question is this -- i have a 100 watt power supply, if i buy a 300watt will it be the same size?? because the inside is tight. i noticed that this computer was running a little warm(not hot). before i had this problem. craig cn60@msn.com craig cn60@msn.com

Chances are you need a power supply. You can use a higher output power supply but it has to match the case. In other words, ATX, Micro ATX, etc...

The red switch is your voltage selector. In the United States it should always be set to 110/115 V (do NOT switch it to the 220 V setting or you may fry the PC!). Also, since you have a Hewlett Packard PC, you will want to check carefully before replacing the power supply; many "name brand" units require a proprietary PSU, and sticking a generic unit in there could also create problems. Check with HP as to why the PC won't power up. I know that some HP PCs have a reset procedure ... might want to check with your vendor. 1 Cor. 15:1-5

Most computers use the same physical size of box to enclose the PS, but on the other hand, you've got a relatively old computer and it might have an oddball size of box. Since you also have a HP computer, there's also a small chance you may have an oddball PS that is a proprietary size, or that has proprietary wiring to the main connector. Most computers use the standard PS/2 size of box. 3 3/8" high, 5 7/8" wide (the side the fan that blows from the case is on and opposite), 5 1/2" long, though the length can vary some. It it a rectangular box with no metal boxy extensions to it that stick out. If your PS box is smaller than that, you probably have a micro ATX PS which is a smaller standard size, or an oddball proprietary size of AT or ATX PS. To check out whether it is your PS that is the problem, or maybe the connections inside your case, see response 3 in this: http://www.computing.net/hardware/w... 100watts is probably too small for your mboard, even if you've got an old computer. 140 watts is the minimum I've seen in similar computers. Check out whether a brand name PS is proprietary. Look up your brand and model number. Hold your cursor over the main connector picture to see the wiring colors. http://www.power-on.com If you have an AT PS, the biggest capacity I've seen is 250 watts, and 200 watts are common.