Blank display , no post , no beep

Check display without cabinet maybe motherboard getting short with cabinet and try new Power supply check all the power supply connectors connected or not .

do you get a 'NO Signal' display on monitor, or anything when booting?
if not check to see if you can see lights on inside the frame? if not, do you hear fan spinning or beeping? sometimes the fan on the heat sink over the processor will stop spinning. the chip needs cooling so if fan won't spin an error will not let pc boot up to save it from getting too hot.
if you can take frame off and find the processor chip on motherboard to see if it is spinning. if not that would stop it from booting. if it is spinning then it is something else like the graphics card failure.

So there is not so much as a BIOS message on screen? Any beeps?
If there is no life at all, you have a CPU/motherboard failure. This may be direct or indirect (e.g. no power to MoBo). Check your connections.
Otherwise, your boot device may not be operating. This is usually a dead or disconnected HDD. Check that it is plugged in. Does it get warm? Can you feel any vibrations from it? It should spin even if your cpu is dead but MoBo is alive.

get a new power supply because yours most likely has become faulty or the mobo is broken

Put just the ram back into the motherboard, the pc will not boot without processor, ram and graphics pluged into the board, check this, if it will still not boot and you still get 3 beeps its a memory(ram) problem, and you will need to replace the memory stick.

check if u r able to open the optical drive if its opening then power supply is gone bad or else get mobo an power supply replace

Hi Durmo, your troubles may be the SLI card. If you are using a single 8500GT make sure your SLI card is plugged into the motherboard as a single graphics card. See page 3-9 in your manual. If your 8500GT has dual out puts check both for display. Only one will show you display.
If you have this set correctly & you have tested your monitor on another system (& it is good) yet no display from the system than contact Asus. This board was make in 2007 & is warranted up to 2010. You can do this online or call Asus at 1-812-282-2787 M-F EST. Other countrys click the dropdown menu at Asus home page. http://www.asus.com/products.aspx?l1=3&l2=11&l3=473&model=1474&modelmenu=1

Post if you need more info.
Good luck!
Mike

While booting BOIS goes for POST check for detecting the all the hardware .

Disconnect all the connection to DVD, HDD, FDD from MOBO.
Rmove all RAM and start the ssytem from testing RAM Serviceability. If you listened a long intermittent beep place a single pices of RAM in MOBO ( repeat test with other RAM also).

Other wise your video card is unserviceable, if you have any addon plugins like NVIDA graphics card you can check

Are you hearing any beeps when you start it up?

Have you tried switching the power supply out with one that is known good?