Ok, got some questions for ya to start:
1. there's no beep codes. what does happen? do you get the "no video signal" msg on your monitor, or just a black screen?
Just a black screen.
2. you say "Second, as soon as I hit the switch on the power supply, the computer starts up." does this give any different behavior than using the front power switch? (does it progress farther, give a post beep, etc)
No. Same behavior, but why does it start up when I hit the switch in back, as opposed to the one in front? Or is this normal for first installation procedure?
Steps and things to check:
1. pull all cables from the motherboard, except the power leads from the PSU. Pull all IDE, SATA, front USB, all of it.
Did that. In fact, the only thing that -was- connected was memory and processor, and the case speaker / power switch.
2. those tiny cables that control HD LED, Power LED, Reset Switch, etc -- make sure they are all connected properly. (this is my foremost area of suspicion right now)
See above. By the by, I've always presumed that the writing on the wires (on the connector) was to face the front of the case. True or false?
3. make certain your motherboard is mounted to the case wall properly, with at least 6 standoffs.
It's got 5, which is all it came with. The front of the motherboard has 3, the back has 2. 3 corners have one, and the middle of top and bottom sides have one.
4. To the motherboard connect power, and insert your video card (unless it uses on-board video), and insert the RAM.
5. make sure the heatsink/fan is properly affixed to the CPU.
6. connect a mouse, keyboard, monitor cable, and power cable and try to boot up, and see if you get a post beep.
I recommend you don't skip anything, like leaving a HD IDE cable connected.
When you boot this config, examine the following:
1. is the PSU fan spinning?
2. is the CPU fan spinning?
3. is there a light on the motherboard, and is it on?
4. does it get a post beep?
Before I got home, the answers were: 1) Yes. 2) yes. 3) No. 4) No. First thing I did after getting home was swapping PSUs. Now I get beeps. So I'm going to work on putting it together now. I'll update with progress.
I was also curious if the fact that it was a Sempron processor had anything to do with it, as the mobo case said nothing about Sempron, just Athlon and Duron. We'll see. Hopefully it'll work, as it'll save me 4 hours of driving tomorrow.
let me know...
