My Computer won't sart, new ps, new MB & cpu

[Gimp]

Hi everyone I'm a newbe to this site and they call me Gimp because I have a gimp leg.
I really need some help before I toss this machine in the trash. Here is the situation. My son fried his computer that I built him last year by hooking up a monitor with a bad cord to a new video card he installed.
His dog was chewing on the cable while it was disconnected from the machine. Well being the nice dad I pulled a new ECS-848-p -mPGA socket 478 mainboard and a new Presscot P-4 3.00g processer out of my closet and put it in his ATX box. I also installed 2g of ddr400 dual channel memory. I PLUGGED IT IN AND NOTHING HAPPENED. I checked the PS by jumping the green and black wires on the power connector. The fans didn't start so I tossed it and bought a 500watt atx PS AND STILL NOTHING NOT EVEN A BEEP. I CHECKED THE SWITCH AND THE WAY I PLUGGED IT IN ,THAT IS OK. THERE ARE NO CARDS PUGGED IN SO I PULLED THE RAM, PS WONT START. I PULLED THE CPU, PS STILL WON'T START I CHECKED THE POWER INPUT CONNECTOR AND THE 12V BOARD CONNECTOR, STILL NOTHING. I PULLED MY PS AND PUT IT IN AND IT WOULDN'T START.

I CHANGED THE MAINBOARD TO A NEW PC CHIPS TIDALWAVE WITH A T12 INTELL 865PE CHIPSET. QUESS WHAT??? YOUR RIGHT STILL NOTHING.
I THINK EITHER THE MAINBOARD IS SHORTED TO THE CASE OR THE CASE HAS A DEAD SHORT IN IT. PROBLEM IS I DON'T KNOW HOW TO CHECK FOR IT DOES ANYONE KNOW HOW TO CHECK THIS OR ANY OTHER SUGGESTIONS. I DON'T THINK I NEED CARDS PLUGGED IN FOR THE POWER SUPPLY TO START.

[Teachingmyself]

You seem very competent but I have no idea what step's you've taken with the mobo so apologies if this seems too simple:


1.Is the P.S.U. voltage switch set correctly?
2.Is the bottom of the motherboard properly insulated from the case?
3.What components have you used since you began?(ie. that you havn't swap-tested)

[Gimp]

Thank You for your response.

The processor voltage is preset but the frequency is jumper select.
I have tried three different CPU's with three different frequencies.

I really didn't want to spend any money but I did yesterday.
I purchased a new board and CPU combination package. It is a
ECS PT800CE-A board with a P-4 Northwood 3.0ghz 800/512 and installed it in the case. Well guess what? still nothing.
I drilled out the rivets that hold the Front plastic cover on so I could get at the switch. I have checked it several times and it seemed OK But that was at the board connector. I checked the resistance at the switch itself and FOUND THE PROBLEM!!!!! The Positive side of the switch had just enough resistance so my continuity tester would not beep or light up But enough for the board to sense a short (2.7 ohms).

Just goes to show always use a meter when testing circuits since it takes at least 5 ohms of resistance to light a continuity tester.

THANK YOU FOR ALL YOUR HELP.
GIMP

[Teachingmyself]

You're welcome,sorry it cost you so much money but hey,you've got the makings of another two pc's now right?Lan gaming network anyone ;)?

Of course there's always the e-bay option too

[goldeagle2005]

Marking thread as solved.

[Gimp]

You're welcome,sorry it cost you so much money but hey,you've got the makings of another two pc's now right?Lan gaming network anyone ;)? Of course there's always the e-bay option too

Teachingmyself ,

I used the parts I had left over and pulled some pci cards out of the closet and built 3 units I put wireless network cards in the pc's and set up my D-link wireless router. now everyone has their own an I only have to pay for one cable internet hook-up instead of 4. thanks