Self-built computer, year old motherboard (Gigabyte - EP35-DS3R), 4 gigs DDR2 Ram, 8800 GT Graphics card.

WAS a 650 watt psu, replaced with 850

My computer recently stopped working out of the blue and I've had this happen before and I just simply replaced the PSU. This time, i've replaced the psu with an 850 watt which should be more than enough and pressing the power button, it sparingly wants to start running and the lights in the case turn off and on. I've tried plugging it STRAIGHT into the wall to see if it's just not the surge protector. ANOTHER odd THING is i'm not getting the little system light on indicating that it's getting power.

I'm somewhat new to building my own computers but i've never had such problems till now.

I guess i should note, i switched it out with a compatible motherboard and it did the same thing.What does "sparingly" mean ? ?

That being asked i've seen brand new PSU's out of the box DOA...well hitting the power button a few times, it finally turns on but obviously it's having trouble wanting to boot up and it either turns off on it's own after about 3 seconds or sits there with the internal lights flickering.