Hi all I need some help. This is the deal. I am building a PC. These are the specs.

Motherboard: ASUS P5N-E SLI
CPU: E6850 w /heatsink
Video Card: 8800 GT 512MB
Ram: 2 gig (2X1) Kingston DDR2 800 MHZ PC6400
Power Supply : Raidmax 500 W

Ok this is the problem. And I want to know what best guess would be as to the trouble.. I put all this together and hooked up the power supply. I could see power was going to the board as the light on the board was lit up. BUT.. when I hit the power button.. everything would turn on for like half a second and then just stop. If I hit the power button again. nothing happened but after about 15 seconds. I could hit the power button again and did same thing. ½ second on and CPU Fan Spinning ETC and then gone. I figured that maybe the power supply was too low or bad so I went out and bought a BFG 650 Watt PSU.. hooked it up and the same thing happened.. can this be the motherboard that is just bad?? I mean I can't get post or BIOS or anything else. The power only stays on for half a second and is gone. Any help would be greatly appreciated. Thanks. .. I have the Ram in the correct slots on the board.

first all is the motherboard sitting on the offset screws that should have come with it? basically you cannot screw the motherboard directly to the case you need to have screws underneath it that crew into the case, then you place the MOBO on these offset screws and crew the motherboard into them, did you do that?

secondly, unplug all devices inside the case, eg CD/DVD/Floppy leve only the hard drive plugged in, if it comes on then you can identify which hardware was causing the issue though trial and error (plug the CD ROM in, power up check if it shuts down etc)

did you bench test the board before putting it in?

also check the CPU and heatsink and correctly possitioned as this will cause the computer to turn off if it overheats.

i had one like this(not same mobo) and it turned out to be because the jumper was missing from the CMOS battery clear pins. Check the jumper is there and in the correct position (not in the Clear position).
I have not heard of a general problem with ASUS on this point but I do recall a lot of people had problems with PC Chips mobos as they shipped with the jumper in the wrong position.

ok first. yes i placed the motherboard on the brass standoffs attached to the case. so the board was not directly attached to the case.

2nd i finally.. unplugged everything on the board except the video card. the cpu and the ram. to see if i could even get anywhere close to the bios. same issue. on for half a second and then off.

cpu and heatsink were in correclty as i checked that as well.

as for benchmarking. dont know how to do that.

also. CMOS jumper. checked that as well . actualy i even cleared the CMOS. i pulled out the battery. set the jumper to clear the RTC and put the jumper back on default setting and put the battery back in. stil same thing.

oh one more thing. jsut to see what woudl happen. i unplugged the video card leaving only the cpu / ram. and turned it on. and i got one long beep. so it realized the card was missing. plugged the card back in and same thing. on for half second then off.

You should ALWAYS benchtest a board before installing it in a case & connecting up the rest of the hardware. That way, you confirm that the board, CPU, RAM & video are all working. Then if it doesn't work after it's installed in the case, you can be fairly sure something went wrong during the install, such as a standoff in the wrong location.

I recommend that you gut the case, lay the board on a non-conductive surface with just the PSU, CPU w/HSF, video card w/monitor, ONE stick of RAM & keyboard connected...nothing else. Turn on the PSU & monitor, then jumpstart the board by momentarily touching a screwdriver blade across the pins for the power switch. If it fires up, go into the BIOS & configure your settings for best performance (i.e., underclock your RAM to DDR2-667, manually configure the RAM timings, lock the PCI-e at 100MHz, disable Spread Spectrum, etc) & monitor your CPU temp. If everything checks out, shut down & install the exact same hardware in the case. Double check that it works in the case, THEN connect the drives & the rest of the cards/hardware.

i DID take the board out of the case and do as yo siad. i had stated that i had only the PSU, RAM, CPU/heatsink Video CARD hooked up. thats it. and it was hooked to the monitor. the only thing i did NOT do was the screwdriver. i simply pushed the power button .. but doing all that i STILL only get the half second on. with only those things connected. and then it turns off. i never get close to the bios.

There is a strong possibility that the CPU is mounted wrong. This is a classic problem when:
>the thermo grease has been installed incorrectly
>the CPU is mounted incorrectly, meaning it is not sitting evenly on the mount plate. If you want a good tut, Google "Arctic Silver" and read over their directions, even if you are not using Arctic Silver brand grease.

What Jam said is right on the target; Here is a link to a step-by-step tut if you are interested:
http://www.suggestafix.com/index.ph...

Give a man a fish and you feed him for a day;
Teach a man to fish and you feed him for a lifetime;
Then industry pollutes the water and kills all the fish.

I agree with ranchhand...if you benchtested & had the same problem, the heatsink is most likely installed incorrectly. Here are the instructions:

http://www.arcticsilver.com/pdf/app...

ok for this motherboard. there is a clip that undoes a plate for the CPU.. you open this plate cover. and the CPU slips into its position. there is like a groove or ridge all around the slot where the cpu is insertedso it slips in easily and snugly. then you put the cover plate holding the CPU in back over it. the CPU is stil showing through this. and then you put the heat sink on top of it. the heat sink came with the "grease" already applied to it so i didnt have to apply any. i secured the Heatsink on the CPU and made sure it was snug. and still have the same problem. thanks for the tutorial. i guess i never really considered that benchmarking but that is one of the things i have done. not hooking up any peripherals and only using the basics first. the only thing i didnt do that Jam said was use the screwdriver.. i just used the power switch. and power came on and then right off.

I would be suspicious of the Raidmax PSU, but the BFG *should* be a good one. You have the 24-pin plug AND the 4-pin ATX12V plug connected to the board? And the 6-pin PCI-e plug connected to the video card?

yes i have the 24 pin and the 4 pin plugged into the power connector on the board and also the connector to the Video card. i took thougth it may have been the Raid max. in terms of quality and power. but it does the same thing with BFG and that is 650 W

I recently had a similar problem with an ASUS motherboard-the P5K. Because it was a returned item, I exchanged it at the store and received a new P5K board. I no longer have that problem. Everything is OK now. While it might be an issue with the CPU or PSU, it is not out of the ordinary to just have a bad motherboard. You should consider getting a different motherboard as an option.

yeah i wil RMA it. i jsut wanted some input as to what i had done and if anyone had any other suggestions. i appreciate everyones help. thanks.

"...unplugged the video card leaving only the cpu / ram. and turned it on. and i got one long beep. so it realized the card was missing. plugged the card back in and same thing. on for half second then off."

If the mboard has an Award bios, and if the latter beep pattern was a beep for a half second, silence for a half second, a beep for a half second, silence for a half second, etc., continous, you have incompatible ram installed, or you have a poor connection in your ram slot(s).

In any case, go here - if the module ID strings are not on this list of compatible modules, whether the ram will work is a crap shoot - random:
http://www.ec.kingston.com/ecom/con...

If you have module ID strings that ARE on the list, or in any case, see response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
http://www.computing.net/hardware/w...
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"everything would turn on for like half a second and then just stop."

On many recent mboards you must have a three wire fan connector connected from a fan to the proper 3 pin header for the CPU fan - if no rpm is detected from that header within x seconds, the mboard will shut down.

The mboard will also likely shut down if the cpu temp gets too high, but the cpu has to have time enough to get overheated before that will happen and that takes more than a just a few seconds if the cpu was cool when you booted.

Check the CPU support list for your model on the Asus site and make sure the one you're using is listed - if it isn't the mboard may not boot. If the CPU is listed but is supported only if you have a more recent bios version, the mboard may not boot if you happen to have an older bios version - in that case you must temporarily install a cpu the bios does recognize no problem, flash the bios to a newer version that supports your cpu, then your cpu will be recognized fine.
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500 watts PS capacity is probably more than you need for this mboard - 430 is probably enough, unless you are using a high end PCI-E card that draws a lot more power and requires an additional power connection to it. A PS can be defective, but you trying a second PS has ruled that out.
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ATX mboards are always powered in some places as long as live AC is being supplied to the PS (and the PS is switched on if it has a switch), regardless of whether the computer is running. You must remove the AC power to the PS whenever you install or remove any connection or component that plugs into the mboard inside the case, otherwise you may damage something.