Did I short circuit my mobo?

[Sgt_Black_Gold]

First, thank you all for taking the time to read and even address my question. I have a late 2010 gaming rig:
Azza Solano 1000 full tower case
CPU: AMD Phenon II x4 965 Black Edition;
Memory: Corsair Dominator 4 GB ram @ 1060 MHz;
Mobo- ASUS M4N98TD EVO AM3; Chipset: NVIDIA nForce 980a SLI;
GPU: 2x NVIDIA EVGA GTX 480 SC
PSU: Cyberpower 950 Watt

Up until a week ago, this PC rig has been working fine without any problems. My power button stopped working (bad wire) so I had to begin starting up my PC by crossing wires. I use electrical tape to avoid further contact. I've been trying to order a new power button, but I think I need to just buy another case.
Now the recent problem... I order a second video card to add a little more horse power and to get better FPS for the latest games.
My second video card did not come with any power cables, so I went to a local pc tech shop and bought an 8 pin connector with 2 molex ends. ....I'm guess you know what I'm going to say next.
After installing the card. I put on the 6 pin GPU power supply for the new card. I turned the PC on and the 2nd card powered up. (Just wanted to make sure I didnt buy a lemon on ebay).
So, after coming back from the tech shop; I powered off the pc and unpluged the power cord. I then added the 8 pin cable to the 2nd video card, then added the SLI band to connect the two card. I then connected the two molex ends of the 8 pin cable to an available power cable on the PSU.
**I then attempted to turn on the PC (by crossing the power wires).....and....NOTHING.....

PLEASE NOTE: The mobo standby light does turn ON.
----To not dramatize this, I will get to the point.....I tried a CMOS check...battery check...Jumping the mobo....still NOTHING. Last night, I went to Best Buy (Geek Squad) and asked them to check the PSU...they did and the PC turned on while using their tester. So I know that the PSU is fine.
This is my opinion leads to only to two outcomes...either the mobo was shorted by improperly using the correct 8 pin cable (or wrong attachment)....or after a year of crossing the wires to turn on the pc...I shorted the mobo. I did get a new power button (clicker)...and that too didnt work.

So, what do you think is wrong? Is it likely that I fried my mobo and need a new one? Does the mobo standby light turn on even if the mobo is fried? Is there a way to test the mobo (i do not have a 2nd pc to try this).

Thanks a million for your help. I sincerely appreciate it!

Thomas
Chicago, IL

 

[cTs Corvette]

Just to clarify, what power connectors do you have connected to the two video cards?

 

[Sgt_Black_Gold]

Hello cTs:

The first time, I connected the two vid cards with the SLI band and then the first card was left alone with the original cables. With the second card, I used the red PSU to GPU 6 pin ...then the black 8 pin split cable with 2 molex ends... I should have waited and purchased the correct 8 pin PSU to GPU....but didnt. Did this answer your question? Tyvm for your help! ~T

 

[cTs Corvette]

Have you tried removing the second video card and seeing if you computer boots on only the original video card? The GTX 480 draws a huge amount of power and I suspect that your PSU just isn't beefy enough to handle both of them.

 

[Sgt_Black_Gold]

Have you tried removing the second video card and seeing if you computer boots on only the original video card? The GTX 480 draws a huge amount of power and I suspect that your PSU just isn't beefy enough to handle both of them.

Yes, I completely removed both GPUs and still no boot. No beeps ...just a standby light. Im 90% convinced I fried the mobo by improperly adding an 8 pin split cable with 2 molex end to the same psu cable. It could of been as simple as having static on myself. This is what I get for trying to save a few bucks buying a used 2nd card instead of buying new. Thanks again for your help!

 

[cTs Corvette]

Using the 8 pin adapter really shouldn't have fried anything, I've had to use them on several occasions.

I know you say you have a CyberPower 950W PSU, but CyberPower makes UPS's and power strips, not PSU's. So the question is, what PSU do you have? (I know you said you had it tested at Best Buy, but that doesn't really mean anything, lol.)