My computer doesn't boot properly!

[Boidi]

So when I turn off my PC after I've finished working, everything turns off without a problem. When I try to turn it back on, for whatever reason, it doesn't boot - the fans spin up like normal but there is no display signal, and I can tell it's not my graphics card as my keyboard doesn't light up like normal. To make it boot I have to hold down the power button and wait until it completely turn off, then I can normally turn it back on and everything works just fine.
My Specs;
Cpu - Athlon x4 950
Mobo - Asus A320M-K
Ram - Corsair 2400mhz 
Psu - Corsair VS350 (I know that's not really a sufficient psu, but everything worked fine for a couple of weeks.)
HDD - 1tb seagate barracuda + 500gb seagate barracuda
All the problems started when I started changing stuff in the bios, i turned on the oc tuner, set my ram to 2400mhz as it was running @ 2133mhz, I turned AMD smv on.
Please help!!

[TehhMiik]

Try reseting CMOS. You can find this in your Mobo manual, or take out and put back the CMOS battery. Hope this helps.