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Power Supply Question

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#1 tigers1829


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Posted 06 June 2009 - 10:18 AM

I installed a new power supply into an existing computer setup because i got a new video card that required more power. After what i am pretty sure was the correct install the computer would not start up. Instead the power light on the computer would flash on quickly when i attempted to power it up and then go right off. Then it was hard to start it again but it would just flash each time. What would cause this?

Additional info: HP Pavilion PC, BFG GS 450 power supply, Visiontek HD 2400 Pro ATI Radeon card, also upon reinstalling the old equipment the PC worked fine. Someone also mentioned something about a soft start being the problem but i dont know anything about this.

Thanks for any assistance.

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#2 fairjoeblue


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Posted 06 June 2009 - 10:37 AM

If the computer has a floppy drive make SURE the power lead is plugged in correctly.

Not trying to be funny but you did remember to plug in the 4 pin "square" connector for the CPU ?

Have you ever seen the video card work ?

Did you hook the power connector to it ?
[I forgot that once]

If you know for a fact the video card is good I would say you got a dud PSU, it happens sometimes.
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#3 disenchanted


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Posted 06 June 2009 - 11:12 AM

"If the computer has a floppy drive make SURE the power lead is plugged in correctly"

Not trying to be alarmist, but if was plugged in incorrectly, don't bother checking the mainboard....being there, fried that...

Here's the Boot Sequence as described in the A+ Certification.

I has assisted me enormously at work, and you can always come back to it for info: (Your system does not even beep, right?)

"What the BIOS actually does during its boot sequence varies slightly from manufacturer to manufacturer; these basic steps are performed during the boot sequence:

When the PC is powered on, the internal power supply initializes.

The power supply doesn’t immediately provide power to the rest of the computer. First, it determines whether it can supply the proper voltages that the PC’s components require. The power supply sends out a POWER GOOD signal when it determines that it can supply reliable power to the rest of the PC. When the chipset receives this signal, it issues a SYSTEM RESET signal to the processor.

When the processor receives the SYSTEM RESET signal, it accesses the jump address for the start of the BIOS boot program at its hard-wired preset address and loads it into RAM.

Remember The jump address contains the actual address of the BIOS boot program on the ROM BIOS chip. The jump address is usually located at address FFFF0 (hexadecimal) or 1,048,560 (decimal), which is the upper end of the first megabyte of system memory.

With the primary part of the BIOS now loaded to RAM, the POST process begins.

If any fatal errors happen during the POST process (problems that prevent the PC from operating normally), the appropriate error beep codes sound or perhaps an error message displays, and the boot process stops. At this point in the boot process, only the system speaker (because it’s technically part of the motherboard) can notify the user of errors.

If all is well, the boot sequence continues, and the system BIOS loads the device BIOS of the video adapter (if there is one) and loads it to memory.

As your PC boots, the video adapter’s information displays on the monitor.

Any other device-specific BIOS routines, such as those for the hard drives or SCSI devices, are loaded.

Information, usually including the manufacturer and the BIOS version, displays. The BIOS begins a series of tests on the system, including a run-up count of the amount of memory detected on the system. Because the display is now available, any errors found in this process are displayed on the monitor as an error message instead of a beep code played through the system speaker.

The system determines whether the devices listed in the CMOS configuration data are present and functioning, including tests for device speeds and access modes.

Remember The serial and parallel ports are assigned their identities (such as COM1, COM2, and LPT1), and a message is displayed for each device found, configured, and tested.

If the BIOS program supports Plug and Play (PnP), any PnP devices detected are configured. Although it usually goes by much too fast to read, the BIOS displays a message for each device it finds and configures.

The configuration is confirmed.

The BIOS displays a summary screen that details the computer as the BIOS sees it. This summary screen signals that the system is verified and ready for use.

The CMOS data contains the sequence in which storage devices are to be checked by the BIOS to locate the operating system. Typically, the first hard drive is listed first, but the BIOS can be set to have the BIOS check the floppy disk, a CD-ROM, or another hard drive first with the order in which the other devices are checked also specified. Depending on the CMOS data, the following actions occur:

If the boot device is the hard drive, the BIOS looks for the master boot record.

If the boot device is a floppy disk or a CD-ROM, the BIOS looks at the first sector of the disk for the operating system’s boot program.

If the boot program is not found on the first device listed, the next device indicated is searched, and then the third, and so on until the boot program is found.

If no boot device is found, the boot sequences stop and an error message (No boot device available) is displayed."

Edited by disenchanted, 06 June 2009 - 11:21 AM.

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