Testing motherboard/parts without a case

I would get it off the couch and place the entire test set up on a table, for starters.

Have you reset the CMOS? Are all the power connectors connected? Did you try only one DIMM? Does the psu meet minimum power requirements?

Disconnect everything so only the essential hardware necessary to boot is installed and connected, i.e.; cpu, 1 DIMM, gpu, and all required power connections. If the system attempts to boot and you can enter the BIOS, the plug the other components in one at a time until it fails to identify the specific component that causes it to fail. If you connect the components in and it does not fail, then you should be all good to go.

Placing the motherboard on the anti-static bag is fine.

Did you install the i5 processor heat sink correctly? Please describe how you installed the heat sink fan (HSF). An improperly installed HSF is one possible cause for the symptoms you describe.

Have you completed the troubleshooting guide listed here:
http://www.tomshardware.com/forum/261145-31-read-postin...

Please report your findings using this form:
http://www.tomshardware.com/forum/264823-31-progess-tro...

Regard the i5 stock cpu fan, it locked in snugly and seems pretty tight on the cpu, and it spun when the motherboard kicked on. The motherboard power on lasted only in 1 second intervals, so I doubt cpu temperates are the issue here. My power supply is 500+watt (which I think is plenty sufficient for my parts), with 24-pin ATX, but I did not have the ancillary power (6-pin I think, right next to the cpu) that Gigabyte mentions as being optional. I assume that is for overclocking and SLI/CF rigs.

I have not done an absolute bare bones start up (1 -Dimm, bios reset), but I'll try that today.

How does a couch and table differ? I actually set it on a large chaise, beause that was the most convinient spot for a available power outlet and the length of the DVI cable from the monitor.

Sounds like this might be the problem. I didn't plug the 4 pin connector, because I didn't have the 8 pin. I'll get back after tonight.

Given how sensitive to static discharge the parts are, placing the test set up on a couch may not provide the best or most stable of platforms for your tests...couch/table/wearing wool socks with wet hands...it's your call...but personally, I would put the entire set up on a solid surface and be sure to discharge myself to the psu before any testing...

This is excellent advice. One of the leading causes of motherboard and other electronic part failures is getting sapped by static electricity. If you live in a cold weather climate this problem is worse because of the low humidity in the winter months makes it easier to build up static charges.

This is what you are talking about:
http://www.tomshardware.com/forum/262730-31-breadboardi...

I think that it is a very good idea to test the parts as much as you can before you gp through all the work to install them in a case.

You cvan make sure that the cooler is installed correctly by inspecting the push pins from the bottom of the case.

It's been so dry in the upper midwest that I'm tempting to do my build in the shower  

Seriously, anti-static wrist band would be a good investment. Just be sure that the chassis (i.e. case) is grounded (usually with PSU plugged in but turned off).

can you tell us what kind of power supply you have? Many 500w PSUs can not efficiently generate the power that they say they can. Also, not plugging in the 4/8 pin ancillary power connector in seems the most likely culprit, as others have said.

It was the 8-pin (dual 12v ATX?) connection that was missing as suspected earlier. When I connected the 4pin one everything worked perfectly without much of a hitch!