I bought an Ultra LSP 650w power supply (upgrade) for my HP a1150y and it won't even boot up (fans come on & thats it). If I put the old 300w (oem) PSU in the PC, it works but it won't meet the power demand of new video card. HP says that the maximum watt PSU I can install is a 450W...can that be right?

Hi

This seems like a power management problem on the motherboard.

Disconnect the power cable. Remove the small silver CMOS battery for 2 minutes to clear the BIOS Memory. Reinstall the battery and reconnect the power.

Look carefully at the power lines coming from the Power Supply Unit (PSU) and make sure that no one power channel is powering an unequal load of devices. Try and divide the load as evenly as possible amonst the power lines.

If none of this solves the problem, then consider upgrading the fitted 300W PSU to one with a higher Wattage, as 300W is on the low side for current standards. 450W-500W is more typical nowadays. The higher the Wattage you can afford (up to a 650W maximum for this particular specification of PC) the better

A higher wattage PSU will work well within its capacity and therefore under less strain than the current one. The symptoms you describe could be signs of the current PSU straining at the limits of its performance range to power all the devices inside as well as maintaining the computer's heavy workload of interaction with all the devices connected to it.

I hope this helps.

Try disconnecting the plug form the motherboard. If the LED stays lit, you may have a problem with something you touched inside. But, if the LED does not come on at all with nothing connected, the power supply is dead. 300W should be enough to run your computer, unless you have multiple graphics processors or too many peripherals, but just upgrading memory shouldn't make a difference. Make sure the memory is seated correctly, maybe try taking them out and putting back in, or check to see if maybe you loosened something inside while you were in there.

You can go as high as you want. Typically the higher the wattage, the more devices you can add as motherboard inputs are standardized so it won't make a bit of difference to the motherboard just so long as you stick with ATX power supplies. So you could go to 650w or even more and it won't make a difference, although you won't need that much wattage unless you have lots of drives and a power hunger discrete graphics card.

You can take it to a computer repair shop. Probably you might have to get it replaced

It is the problem with your motherboard and not with the Power supply. I know It sounds silly but this is true. Please get the motherboard repaired

HI DUDE .. I JUST GIVE suggestions Boss Car Audio D5504 "Diablo Series" 4-Channel Car Amplifier 2200 Watts ITS REALY GOOD FOR SOUND SYSTEM DUDE

Believe it or not, it's due to a weak power supply. More specifically, weak voltage rail/s caused by failing Electrolytic Capacitors.

A bad computer power supply is about 70% of computer failure.

ALL the light use less than 1 Watt. EACH fan uses 2 to 3 Watts.

A processor uses 55 to 125 Watts. Depends on the make and model.

Since the power supply is weak, it doesn't have enough power to turn the processor on.
No processor, nothing to find the Boot record on the harddrive. Nothing to get the Operating System going. (Example: Windows XP)

No computer running, there is no signal to the monitor.
Just enough power to light lights, and spin fans.

In many cases the additional 4 pin section slides up and off of the main power plug for use in your particular unit.

Hipro- HP-P3527F3W
is the replacement for Bestec 300W

it is better to use the old power supply because it is compatible to your mother board