If you pull all the memory and power on, do you get three beeps? If you do, the motherboard is okay, but you may not be getting enough power on the memory and processor rail. How many amps does that power supply support on the +12V rail?
There were no beeps without memory, or without memory and CPU. However, if I reseted CMOS, next boot was successful (but only until clean shutdown from OS or power loss). Changed chassis to SC5650UP - system boots without problems. Was there something "special" in power supply, or in case itself? HiPro PSU specs in SC5650UP are not impressive - for example, +5Vsb 2.5A instead of recommended "at least 3A".
Corsair VX450 specs are: +3.3V 20A, +5V 20A, +12V 33A, -12V 0.8A, +5Vsb 2.5A, ATX12V v2.2
In my case problem was solved by getting certified chassis, but it would be interesting to know, what caused it.