New Motherboard Replacement, No Boot (Originally HP a6720y)

[abc617]

This is the first time I've had to replace a motherboard with this type of system and I'm having a bit of trouble.

I have a HP a6720y [http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01643511&lc=en&dlc=en&cc=us&product=3856272] who's original motherboard died. So I got a new motherboard that looked to be compatible with it, and ASUS M4A785-M [http://www.newegg.com/Product/Product.aspx?Item=N82E16813131595].

I installed everything and managed to get the system to power on (CPU and case fan), but it doesn't seem to boot up to anything. I've tried resetting the BIOS by switching the jumper and leaving for 5-10 sec, then switching it back, but doesn't seem to fix it. I've tried with booting up 1 stick of RAM, none of them work. Here are the components I have:

I unplugged any other component that may have been unnecessary to starting up the computer like the optical drive, front side USB, card reader wireless card

-HP Pavilion a6720y case [original]
-2 x 2GB Samsung M378T5663EH3-CF7 - RAM [original]
-2 x 1GB Samsung M378T2863EHS-CF7 - RAM [original]
-SAMSUNG HD642JJ 640GB 7200 RPM - HDD [original]
-ASUS M4A785-M - Motherboard
-Bestec 300W ATX0300D5WC ATX Power Supply [original]
http://www.censuspc.com/product-pr-11669.html

I know this is a really rough description of my problem. I'd appreciate anyone who may have a little insight on why its not booting up and any solutions you may have. Thank you.

 

[g048989h]

Did you reinstall the OS? Probably need to cause old bios and drivers are still on hdd if you didnt. Those drivers and bios wont work well with new MB. I dont know how to get rid of bios without formatting and reinstalling OS. Once thats done, load the new MB drivers and bios

 

[abc617]

Well I can't even get anything on the screen to show up. The thing I forgot to mention is that my monitor doesn't receive a signal. When I first start up the computer, the keyboard lights will blink once, and then nothing. No signal to the monitor, buttons don't do anything. And I can't hear a beep from the computer, so I can't hear if the system is beeping to tell me know there is something wrong with that components or something. There is an old OS on the HDD, but I doubt that will prevent the system from even booting up to a BIOS screen or outputting a signal to the monitor.

 

[g048989h]

Hmmm...... The MB tells the montor to turn on, it tells the system to turn on.. Nothing works without the software. Did you load the new drivers for the new MB? if not, I'm standing firm. even if you did, trying to run dual bios is tricky unless the MB supports it as a feature set. I might be way off here, but I personally have always loaded a fresh OS and formatted the disk then loaded the new MB drivers when making a change like you made. I would think this would be especially important on an HP or similar becasue they are SOOOOOO proprietary.
anyone else got ideas???