Attached, detached, and reattached everything (reseating motherboard, CPU, and RAM) about four times now.
Detached reset button from motherboard front panel connector
Used different data cables and power cord
Used a different (new from Best Buy) PSU (Thermal Take Smart M 850W)
Verified HDD is recognizable in another computer
Built system in the case and out of the case.
Reset the CMOS by touching the jumpers together and by removing the battery.
Held the power button while the power cord was removed.
Powered on with one stick of RAM (in all possible stick/slot combos) and both sticks.
Power on with no RAM gives three long beeps. Any other power up gives silence and nothing through VGA or HDMI output (tested both monitors with other inputs and they each work).
Every time I power on, I can get solid power light, CPU and PSU fans spin, Optical Drive lights up and can open/close, but no HDD light and no output or successful POST beep.
Any ideas of solutions I haven't tried yet or for which parts I should start asking for replacements first??
Just to make sure, you had no other perephrials attached? I've seen some powered USB hubs feed back electricity into systems which have prevented them them turning on. Also, no silly mistakes like forgetting the 4pin 12v power connector near the corner of that board where the ps/2 connector is?
With different results from having no ram installed, and failed boots with having ram installed, I'd try getting your hands on some other memory to try, might be some compatibility issues with the timings.