I'm having the same problem, fans come on drives spin up but no post. I have tried everything; three different PSU, four different brands of memory, three video cards (one PCI), and two motherboards and still the same thing. It just beeps, I'll check tonight to see if the beeps match any from the Phoenix list, but I'm guessing they won't. I'm going to look for a CPU tonight, but I don't think anywhere close carries them (maybe CompUSA but I'm not sure about their return policy on CPUs). I'll probably have to go to Fry's this weekend.
One other thing that just started with the new motherboard that I got yesterday is that the PSU turns on as soon as I switch it on the back, I can't turn it on with the power button on the case. The front panel connectors are hooked up correctly, the LEDs, speaker, and reset work.
Here is the hardware I've tried;
Motherboards
Chaintech VNF3-250
MSI K8N Neo Platinum
Memory
512MB Mushkin PC3200
256MB Kingston PC3200
128MB Crucial PC2100
128MB Infineon PC2100
PSU
Thermaltake 420w
Thermaltake 480w
Mad Dog 500w (bought at CompUSA and returned after the same problems as with the other two)
Video Card
Geforce 3
Voodoo 3 3000 PCI
Geforce 5200
The CPU is a Sempron 3100+ and the case is a Cooler Master Cavalier.