My specs are:
OCZ Power Supply
Radeon HD 4830 512MB GDDR3
Intel core i5-760 CPU
Caviar Black SATA HD 7200/64MB/SATA-6G
HP 24X DVDRW SATA
OCZ 4GB DDR3- 2 RAM sticks
Also my motherboard has 6 channels SATA interface and satisfies SATA 2.0 specs with transfer rate of 3GB/s and my hard drive has an interface of 6GB/s. I think these are compatible but this might cause the problem???
Your point about PSU might be right because it happens quite a few times that when I plug it in again or push it properly the system boots up but there is still some doubt since it does not happens always. Sometimes I have to switch the power button multiple times before it starts to boot up. Also, I have no idea about why those LEDS are not lit!!