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Pc will not boot when power supply from dvd drive used for new device

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February 27, 2010 6:34:53 AM

Hello, I'm struggling a little here, any advice would be welcome.

I've upgraded motherboard and CPU and graphics into a Vista Business system - worked fine with no repair/reinstall process.
GIGABYTE GA-MA790XT-UD4P
Phenon X2 965 Black
Powercolor HD4850.
I needed power for the card so have used a 2 x4 pin into 6 pin adapter. This meant I had to remove power from my Coolermaster Musketeer but this has always been very useful in keeping case-fan speeds (noise) down. I've tried taking power from one of my optical drives but the system won't boot past the BIOS screen and I have an HDD LED lit permanently. If I put the power back into the drives, it's fine. Both power connectors for the optical drives are on the same rail. The power I have removed has been to the slave drive.
Does anyone know why it won't boot? Thanks,
a c 248 ) Power supply
February 27, 2010 7:06:27 AM

Please post the brand and model of your power supply. The information should be on a data label on the power supply.

A system with one ATI Radeon HD 4850 video card requires a 450 watt or greater power supply with one 75 Watt, 6-pin, PCI Express® power connector.

Modern power supplies come with at least one 6 pin, 75 watt, PCI-e connection and power cable. It sounds like your power supply did not so you used a molex to 6 pin PCI-e adapter cable. The two molex connectors on the adapter cable need to be connected directly to the power supply. I am not 100% positive but I don't think a video card can share power with another device. At least I've never read about it being done.
February 27, 2010 7:38:10 AM

Thanks.

The PSU is the stock unit that came with the machine way back. FSB Group, 350W ATX-350GTF. No 6 pin power at all.

Correct - I have used a 6 pin PCI-e adapter cable.

To clarify, the video card isn't sharing power - I had one spare rail with two connectors, one of which was powering the Musketeer. They are now both running into the adapter and powering the video card - this is working fine.

I'm just confused that in removing power from a DVD drive (that I don't need) and routing it to the Musketeer unit would stop the machine booting.

What I haven't tried, thinking about it, is removing the power from the DVD but not connecting it to anything else before starting...

If I'm wrong about the DVD that I've disconnected being the slave, would the mobo refuse to boot the machine without a master optical drive in place?
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February 27, 2010 7:52:01 AM

Could limited PSU be the reason that startup take a long time also....?
a c 248 ) Power supply
February 27, 2010 8:36:56 AM

Trying to start the pc without power to the Musketeer and an optical drive sounds like it might be worth a try. Let us know what happens.

There may be another problem. I checked several references. Your power supply is a model from six years ago. It is an entry level psu that was not designed for use with modern video cards requiring a 6 pin, 75 watt, PCI-e power connection. In addition it is a 350 watt psu. The recommendation for a system with a 4850 video card is a 450 watt or greater power supply with a PCI-e power connection and cable.
a c 243 ) Power supply
February 27, 2010 10:08:33 AM

mynameishenry said:
Could limited PSU be the reason that startup take a long time also....?

Your psu only has a single 12v rail, rated at 15 amps, yes it's the reason.
February 27, 2010 10:14:15 AM

Thanks JohnnyLucky - will try other startup tests later....
!