Newly built computer doesn't turn on.

By ryant.leary ·

I've recently put together a new computer; as far as I know, everything is plugged in correctly, but it doesn't work. The motherboard, processor, and RAM were all installed and verified as functional by the people at I plugged in my 2 x 12, 1 x 4, and 2 x 2 power cables, and I connected the front panel cables to the best of my ability -- the power switch and reset switch cables are where they belong, and I believe the power LED and HD LED are properly connected also. The power LED light turns on, as does the light on the motherboard. I can find no reason why the computer shouldn't start, but when I hit the front panel on/off switch, absolutely nothing happens. Does anyone know how I can locate the source of the problem? Thanks for your help.

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All Answers

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Well if you told us what the M'Board is we may be able to help you here

by OH Smeg In reply to Newly built computer does ...

But if this was passed as Functional with the RAM, CPU and Heatsink/Fan the only things left are that these is a Short Circuit owing to the M'Board being incorrectly mounted in the case or the Power Supply isn't working or the Front Panel Leads are not plugged in correctly or incompatible Hardware something like a Video Card not being compatible with the M'Board.

Have you looked at the fan on the CPU Heat Sink? When you press the Power Button does it spin at all?

Nothing else that it could be I'm afraid.


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by ryant.leary In reply to Well if you told us what ...

The motherboard is an Intel DP45SG. To ensure no incompatibility issues, I removed everything -- now I just have the processor, motherboard, RAM, power supply, and front panel leads connected. While plugged in the motherboard light is on. When I press the power button, the front panel LED lights up, and it beeps twice: first it's short and high-pitched, then a lower beep that lasts a little longer. The fan on the CPU heat sink does not spin at any point.

I'm very grateful for your help. I'm no good at this stuff -- I'd built a computer once before, but everything just magically worked when I plugged it all in. I'm completely at a loss here. Thanks for your advice.

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Try this

by wanttocancel In reply to Update.

If you have more than one stick of RAM remove all except one stick and try to boot the system. If the system starts then you have a bad stick of RAM. Go through this process until you have tried to boot the system with each stick of RAM. I know that you said that you checked the RAM and the mobo with Mwave but you have to make sure.

Per Intel's website two beeps means a parity error. Here's a listing:

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These Intel M'Boards have

by OH Smeg In reply to Update.

2 Power Connectors one is a 24 PIN ATX Connector and the second is a 12 V DC 4 pin connector you need both plugged in to allow the M'Board to work. The second Plug has 2 X Black and 2 X Yellow or Yellow with a Black Trace Wires.

If that is not the problem double check the supplied components the Supported Processors for this M'Board are listed here

The supported RAM and it's configuration is listed here**51.htm

More importantly the Beep Error Codes are here so read these and see what the BIOS Beep Code is attempting to tell you It is on page 71 of the Users Manual or here

and you will have to go to page 71 to read it. :)

The Front Panel connectors are listed on Page 44 of the Owners Manual and the Reset and Power Switches can go on either way but the Power & HDD Activity LED's are Polarized Components which means that they have to be fitted the correct way. This means that the colored lead from that LED goes to the + Pin. For that Power LED this is Pin 1 on the external Connector The group labeled G or Pin 2 the group Labeled H on the Front Panel Connector, for the HDD this is Pin 1 Numbered on the Front Panel Connector in the H Group on page 44 of the Users Manual.

Though if both are incorrect the CPU Fan should still be working. If it isn't and the second Power Connector is plugged in you have a Faulty M'Board or a Bad PS which is unable to provide the necessary power for this Unit.

Also as this M'Board supports Dual Chanel RAM you need to 2 Sticks of Identical RAM fitted tot he Blue Sockets on the M'Board. If you only have 1 or 3 Sticks of RAM the M'Board will run in Single Chanel Memory Mode and be slower than it should be by 50% of the Front Side Bus.


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Thanks, finished.

by ryant.leary In reply to These Intel M'Boards have

Thank you both for your assistance. I played with it for a while longer today and I've concluded, with the help of an Intel chat representative, that my video card is incompatible. It's incompatible because it's the only piece I hadn't recently spent $100 on. How foolish of me!

You guys were wonderful in helping me diagnose my problem. Thanks again.

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Your Welcome

by OH Smeg In reply to Thanks, finished.

Though you can pickup a 512 MEG Video Card quite cheaply these days. A Gigabyte ATI HD4350 retails for $89.00 AU and has the following specs

Overclocked PCI-E 2.0 512MB 64-bit GDDR2, Dual Link DVI-I / D-sub / HDMI / HDCP, Fan

or if you like NVidia you can get a Galaxy GF 8400GS PCI-E 512MB 64-bit DDR2, CRT, HDTV, DVI, Fan, Includes 2x Low Profile brackets. for $69.00 AU which is less in American $. :)


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Vid card replaced, problems persist.

by ryant.leary In reply to Your Welcome

Hi again,

Having now bought a new video card, I have officially replaced everything. I certainly have no compatibility issues now, as I did before. However, I still have a problem. When I turn the computer on, I hear a siren, which I've read implies the processor is overheating. I've already reseated the heatsink, as per an Intel rep's request, though without replacing the thermal paste junk. The processor's fan runs, and it has the same set-up as a previously functional computer in terms of air intake and so on, though the rear fan and fan on the new video card do not function. I believe the rear fan's power is plugged in properly, and I can find nothing on the video card for me to alter to attempt to get that to work. I am now again completely at a loss. I would be grateful for any further assistance you can offer. I don't think I'm going to build my own computer in the future; this has been a complete mess. Thanks.

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dont let a small thing like that stop you

by XnavyDK In reply to Vid card replaced, proble ...

I bet you have learned a lot though this. Next one will be easier. I also bet you found out its a lot more complicated then people think especially if there is a problem. Just FYI the temp sensor for the cpu could not be in place or is malfunctioning or is not even plugged in which will give you the siren. But wait for Oh Smeg, he knows more about this then I do. :-)

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Also, if the Vid Card fan isn't spinning......

by ThumbsUp2 In reply to Vid card replaced, proble ...

The card either isn't seated properly, it's the wrong type for the slot you've put it in, or it's defective.

What card did you get?

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RE: rear fan and fan on the new video card do not function

by OH Smeg In reply to Vid card replaced, proble ...

That sounds very much like the supplementary 12 V DC Power Supply Lead isn't plugged in. This is a 4 Pin Plug with 2 Black and 2 Yellow or Yellow with Black Traces going to it and is located slightly to the front and above the Back Panel Connectors as the M'Board sits in the case.

If this Plug isn't plugged in there will be no 12 V DC Power Supply tot he Various Sockets including the PCI E, the PCI or Fan Power Plugs.

So look at the M'Board closely and make sure that you have this 4 Pin Supplementary Plug plugged in. If the Power Supply doesn't have one it is not compatible with the EP 45 Chip Set M'Board that you have and needs to be replaced not have a Adapter fitted as this will draw all the 12 V from the one rail and not have 2 12 V DC Rails int he PS Feeding it.

As for the Alarm going off this could be the CPU Overheat Alarm, the CPU Fan Alarm or any of the other alarms that measure Fan Speeds or Voltages on the M'Board. For an Initial Boot up you don't worry about Alarms till after you set the BIOS and disable any Alarms that have nothing connected to the Plugs on the M'Board things like Case Fans this involves.

I would say it is a Under Voltage Alarm trying to tell you that the 12 V DC Supplementary Power isn't connected. Fans not running on the Video Card is another give away here and if the Case Fan is plugged into the M'Board that is yet another Symptom that tells you that there is no power available to part of the M'Board.

If you try to rely on just the 24 Pin ATX Socket it can not provide enough power to the entire M'Board and will cause the Tracks to malt if the M'Board works at all. I wouldn't expect one of these Chips Sets to work without the Segmentally Power Connected. Intel has done this to prevent M'Board damage with the EP43 Chip Set M'Boards and I would expect them to have continued that Design Improvement to the EP 45 Chip Sets as well though I have not as yet had the need to use one. If the customer wants anything higher than a EP 45 Chip Set I use the new 1366 M'Boards.

But the EP 43 & 45 Chip Sets do have a dedicated Power Supply made for them and the AMD Equivalent. No M'Board maker will offer any Guarantee on any M'Board if the correct Power Supply is not used and they can see this on any Faulty M'Board returned.


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