Hi. Thanks to everyone.
I re-described the problem and what I've done already. Basically when I switch the PC on, only thing what is happening is that CPU fan starts blowing and I'm also able to open CD-drives (that means that PSU is working and supplies electricity to MB and peripherals). Even BIOS wont boot up. Tried different AGP graphics card - nothing. So first thought was that MB is faulty now. I bought new MB, took old one out and put new MB inside the case and plugged everything back (so all cables are checked). Meanwhile I tested this HDD inside other PC and it was working. The new MB is with onboard graphics (didnt plug AGP-card on) and everything else plugged in, swithed the power button and result - nothing again. Wont boot up even to the BIOS. Then removed HDD, floppy, swapped over RAM and no result. I also used multimeter to check the voltages what are coming out from PSU and going to the MB, everything seemed OK.
Now questions: Should I be able to get something to boot up if I remove HDD, floppy, RAM and CPU. So basically its just bare MB. Or do I have to plug something in to get the first boot? How about CPU, if this is burnt, should I be able to boot up to BIOS?
Regards,
Kirret