installing a motherboard - problem

[pronane]

I recently bought a kv8 pro amd athlon 64 754 motherboard off  ebay. It appeard in box and the owner said it was new and un-used. So I went and bought a case with a 400w PSU. WHen i went to connect the PSU to the motherboard, i noticed a yellow 4-pin plug cellotaped to the main power plug that gets plugged into the motherboard. THe letters 20+4 was written on the end of the cable head, what is the extra 4-pin plug for?

ANyhow i installed ram and i installed a video card, and the processor and heatsink obviouslly ( though the fan is not very secure in place! ), and went to turn on the box pressing the switch at the back of the PSU ( then pressing the switch at the front, which does nothing at all there is no response from the motherboard ), all that comes on is the green light on the motherboad and down in the "post code" LED thingie what resembles 2 letters 'JJ' or upside down 7's!!! There is no noise off the motherboard to suggest it is loading up or doing anything. what am i doing wrong? what do i need to check for? is the motherboard dead?

Just to note that the PSU fan doesnt even come on.....any help is greatly appreciated!!

[street1 (RIP)]

Do you have a place on your motherboard labeled 'ATX12V1'for that 4 pin connector you haven't used ?

[Deerpark]

This should be your MB, correct?

You need to plug that 4 pin connector in where I've circled.

[street1 (RIP)]

Deerpark has it. A picture is worth a thousand words.

[pronane]

i connected a white 4 pin plug ( that was seperately connected to the PSU ) to the atx12v nothing happened bar the led on the motherboard coming on, and i connected the yellow flourescent one you will see in the plug below but still nothing happens save the led coming on on the motherboard and the "post code " light thingie in the bottom left corner:


http://i6.photobucket.com/albums/y236/pronane/Image058.jpg

yes that is my motherboard

[Deerpark]

You say that when you press the switch on the front of your case nothing happens? First of all we need to make sure that the switch is connected correctly to the motherboard. There should be a diagram in your manual that shows which pins the power switch needs to be connected to.

[pronane]

althought there is no cable connected in this picture, if i connected either the white one or the yellow one ( 4 pin ) this is all that happens, led light and something that resembles a J in the post code thingie.

http://i6.photobucket.com/albums/y236/pronane/Image001.jpg

[pronane]

deerpark its down in the bottom corner, the Fpanel is down around where you see that j, and i have connected it as described in the manual.....but nothing happens when i click the on switch.

Does this look like an error between chair and keyboard or is the Mboard fooked?  why doesnt the fan come on on the PSU at least?

[honvetops]

sorry to bust in here but my 2 cents with this problem I have had on 2 builds*

1. the fan has to be seated correctly and tight to the heatsink  (cpu) some units are hard to fit together or "snap" in but that is critical to get the connection operational

2. most of my issues on initial setup were incorrectly placed  "case" wires from the case to the clear pins on your mobo  < check those out closely, make sure all the positive & negative wires are seated on the correct pins     <  this one has caused me weeks of lost time!

the 4 pin is for extra juice to the cpu >  ie....

    * The 20-pin (or 24-pin) motherboard power connector.
    * The 4-pin auxiliary power connector, which supplies extra power to the motherboard to cater for modern AMD and Intel CPUs.

most of my experience on these snags were dumb little things overlooked 

[pronane]

hmm the power cables i have look like this

http://www.pctechguide.com/images/tutorials/MBoard/Power.jpg

but i have 2 extras called +p led, -p led.....the thing is on the mobo i have it doesnt mention anything about these, all it mentions is about Suspended LED, speaker, GURU, HDD LED, power switch and reset switch but there is nothing for +p led and - led, could that be whats wrong?

i am having problems getting the fan and heatsink to stick in i think.....i am not sure its properly in, its a bloody bastid to get in. The instructions are a diagram with no words, and i beleive i have followed what it says but i am not convinced....

thanks for the reply guys.

[Deerpark]

Yeah it's usually some stupid little mistake, but it can also be a compatibly issue or a bad piece of hardware. But lets try and eliminate all the stupid little mistakes I've done when doing custom builds.
And on that note you should make double sure that everything is seated correctly.

And can you post the full specs for the build?
Like the exact model of the cpu, what kind of ram you have, the wattage on the PSU, etc.

I think +p & -p refers to to the power LED. I.e. the power indicator on the front of the case.

[pronane]

ok the ram is 256 266 mhz ddr ram. the video card i cant remember cos its from an old pc but i think its a geforce 64mb ....something... cant remember full specs, the cpu is a 2800+ sempron processor, the PSU is a 400W mercury.  i think thats pretty much it.

i am pretty sure its all seated correctly.....but i dont know if i mentioned even when i turn on the power supply unit switch, the cpu fan doesnt come on.......shouldn't that come on no matter what?

even if you dont have the heatsink and fan connected porperly and you plug the cable from the fan into the motherboard, should the fan still come on and spin?

this is really frustrating as i have bought lots of different crap to get this working ( that i wont need if the motherboard is at fault ) and it appears to be the motherboard....

[pronane]

i actually have another question, why was there a yellow 4 pin plug connected directly to the 20 pin main PSU plug?  ANd also what was the other white 4 pin plug for if that yellow one is meant to be used in the atx12v socket?

[Deerpark]

Both plugs is for extra 12v juice for the CPU, some new CPUs requires both. (Like the Core 2 Duo if I remember correctly.)