The issue appears after I upgrade my memory from Kingston DDR3 1 DIMM 1024 @1066 MHZ to Corsair DDR3 2x1024 @1066
First time when I press the power button the system was on ( lights and PSU) but I can't hear the BEEp ( boot sound ) and screen was black. After I press the restart button computer boot normaly. What I do:
1. I remove DIMM's and try to start without them, computer BEEP 3 times indicate the missing hardware component, so far so good.
2. Check BIOS version (that was upgrade to latest ver. downloaded from ASUS website) no overclock was made, I left everything auto, or default; Still can't boot.
3. Unplug all compenents like HDD, DVD\RW to verify the overload of the PSU, still no result, sistem doesn't boot even if I unplug those devices and left just the MB powered.
4. Check the PSU voltages, their was in normal parameters 12V MB 1.5V RAM, 1.35 max for VCORE.
5. Temperature of the CPU is 18 idle and 27 full loaded, MB 35 constantly.
6. Test memory with MemoryTest86, no errors foud.
7. Try different slots for DIMM's (dual channels) , Still nothing changed at first time boot.
8. I downgrade the BIOS to an elder version, nothing changed.
9. I reset the CMOS and still nothing changed after that, no but at all.
I had a bad feeling about my PSU, that I already checked and still nothing, but my feelings tell me that cause all the problems.
ANOTHER FACTS, anytime I restart the OS, system starts normaly. When I shutdown the system, bang, dead.
I can still start my computer by pressing the power button, wait aprox. 2 min and then when I press the reset button system boot normaly without any issues
P.S. With Prime95 system is very stable, stress it about 5 hours and no errors occured.
If no bios POST then back to basics.... disconnect all USB devices, disconnect everything including hard drive... with just the CPU, RAM and Graphic card you should be able to get the bios to POST (Power On Self test) and be able to enter bios set up screen if so wished, this must be your first goal.
So... we are looking at CPU, RAM, mobo, Graphic card or Power supply, what you really should have done rather than flash the bios was to re-inset the original RAMs since everything was presumably working till the RAM upgrade...
... flashing the bios should never be done lightly and without a definite reason.
Lets suppose all was well with just the bare bones, the computer will boot bios and hand control over to the CPU and nothing else... because the ain't no hard drive connected, you would see a message something like 'Hard Drive Failure', 'Please insert your disc with the operating system on' etc, the bios would let you know about it.
The extra RAM could easily put a little more strain on the power supply, more so if it isn't relatively new... aging capacitors for example allowing excessive hf ripple on what should be a dc supply line.
Have you tried re-seating the video card and checking the FSB clocking speeds, some mobos uses links, DIL switches or done automatically in bios.
Come think a identical post somewhere in the last week or two turned out to be a duff RAM, but the fault was no boot at all.
Startup issues 
Linear Mode
