Are you seeing any signs of life such as the fans running in the system? If you press the button on the PSU does the green LED light up and do you hear the fans? Try pulling all the RAM modules and then boot the system. You should get a series of beeps or diagnostic lights showing that the MB detects no RAM. If you get nothing and the PSU tests fine then it could be a MB problem. You can also disconnect power from all the drives, GPU, etc. leaving only the MB connected to the PSU. If the system boots then you start connecting those items one at a time until the system fails to boot. Once it fails to boot, you have found the bad component.

The system is not very old so the CMOS battery should be good but just to rule out that out as a cause you can replace the battery with a brand new recently purchased battery (CR2032).

Hi JOcean,

I did try pull out the ram and turn on the computer, it did give the amber light code for ram problem. So, I assumed the motherboard is still ok.

I will try your sugestion and update you the results, thanks for your response! Much appreciated it

I have tried your suggestion, and the MB doesn't send any series of beeps or diagnostic lights after I remove Ram, VGA, and SSD. But the power is on and the fan also run. Is it the MB problem?

I have dealt with two 7810's in the past month with a smattering of different problems. Looks more and more like that.

I have dealt with two 7810's in the past month with a smattering of different problems. Looks more and more like that.

@bbrown82 Me too. I guess Dell planned to make their production disfunction once  guarentee peroid expired.

Here is my experiences:

1. About ten years ago, my Dell game laptop computer can not display. Luckly only one month left in guarentee peroid, so they replace the screen and no fee paid.
2. About 3 years ago, in our office, the DP port cannot work on several Dell U2515H display; And most of XPS 8920 PC failed to boot randomly.
3. About 2 years ago, my home server R420 cannot boot even RAM and CPU replaced, I've to buy an used one and unfortunately it live in my home only two days and then dead.
4. In last year we got two used workstatioins T7810 and T7910. The exactly same K1200 graphics card  can works in T7810 but T7910, we've to buy a new card to feed T7910.
5. In recent two days, the T7810 cannot boot: fans run normally, the power is about 160w, but both disk LED and Power LED are solid on. According to Dell official manual, solid white power LED means run normally, but actually, it failed to boot! Almost all ways I can found tried, it still cannot boot!