I am in the process of building a new system from scratch. I'm sure the answers to my questions are in the forums somewhere but searching for them takes forever. I started out by purchasing a Gigabyte mother board (GA-790XTA-UD4), an AMD PHENOM II X4 955 3.2 GHz processor, 8 GB Kingston DDR3 1600 memory, an LSP 750 Pro ATX power supply (750 watts, lifetime warranty), a Hitachi 1TB SATA HD, an LG DVD Optical drive and an NVidia GeForce 8400 GS video card. Once the components arrived I "bench" assembled them per the motherboard instructions. I turned the system on and nothing happened, no display on monitor, no post codes, nothing. I should note that although I didn't install the motherboard in the case I did connect the front panel switches and cables, case fans, etc. with the motherboard well insulated from contact with the case. All fans connected came on (CPU cooler, video card fan, case fans) and the hard drive was quietly running. After many long minutes checking all components and connections I could not find anything obviously installed incorrectly. Contacted the Gigabyte Tech Support web site and was given some instructions on trying to isolate the problem. None of their suggestions worked (changing out memory sticks trying each one separately, resetting CMOS). I was then informed that the motherboard must be defective. I returned the motherboard for an exact replacement. After replacement motherboard arrived I went through the same procedures again. Results were the same. I then returned the original CPU and ordered an AMD PHENOM II X4 965 3.4 GHz processor. Installed in 2nd mobo and the results still the same. I should note that by now I was now testing with only the cpu, memory and video card (no onboard video). After hours of frustration I returned the 2nd mobo and ordered an MSI 790FX-GD70 mobo. Results??? The same. Even though I had tested the original LSP power supply and found the voltages to be right on I borrowed an Antec 500 watt supply from a friend just to make sure it wasn't a power supply problem and still got the same results. I contacted the MSI Tech Support web site and was told it points to a bad mobo. I cannot believe that 3 out of 3 mobo's are bad and that somewhere along the line I'm doing something wrong. I've build several systems in the past but have never run into a situation like this. Any and all help would be so appreciated. Thanks for listening. BTW - I know someone might think the CPU was installed incorrectly but by experimentation I found out that one can't install it incorrectly. It only fits one way, with the arrow on the CPU aligned with the arrow on the ZIF socket.
Albeit possible to have three DOA mobo, in a row no less, it is highly unlikely. Instead of using the case power button, use a flathead screwdriver to jump the power switch pin on the mobo. 3 of 3 boards, different PSU, and breadboarding (out of case build) indicates failure with one of the components that weren't replaced yet.
According to your statement, you've only replaced the mobo and PSU. If MSI mobo also doesn't have on board video chipset, see if you can borrow your friends GPU. Also worth considering is testing your RAM in your friends build, but be mindful of the RAM specs. Meaning, if your friend's BIOS is supplying different RAM specs, using your RAM w/o setting your RAM specs may damage his/her system.
Thanks for the response. Chalk this up to old age and lack of knowledge of recent motherboard technology. I haven't put together a system is 15-20 years. Back then there was only one power connector from the PSU to the Mobo. When I connected the 24 pin connector to the mobo this time I thought I was done. It took a new set of eyes from a younger system builder to ask the question, "Did you connect the 4 pin power connector to the mobo?" Not being aware of this "new" (probably new only to me) power connector I had not done so. Lo and behold with it connected the system works. Needless to say, this old man is more than red faced. I've gone back over the instructions with the mobo and PSU and sure enough they both mention it but being unaware of the additional power connector (an important 12v at that) I just plain overlooked it. Hard lesson learned.