xps 435t-9000 random shutdown solid amber power button

Hello,

Hoping someone here can offer some advice? I recently replaced my harddrive and since then (don't know if it's a coincidence or not) I'm having another problem. After I installed it, the first time my computer went into sleep mode/hibernation I couldn't wake it up. Power light was flashing white. Eventually I shut it down manually and then it wouldn't boot. Had a solid amber light, no power except the power supply. Fans not working. I unplugged everything and made sure it was all good. Wouldn't start. Left it overnight and plugged it in the next morning. Started up. Worked great for about 7 hours and then just randomly shut down, no errors or anything. Same deal. Wouldn't start, amber solid power light. Let it sit for awhile, reseated everything and wouldn't start.Gave up for awhile, tried a few hours later and it started. I read a few boards pointing to the power supply being bad or not powerful enough. However, I replaced the power supply about 6 months ago with a Corsair 600 which is plenty power. Could still be an issue perhaps but seems odd it would die in that little time. I also replaced my graphics card if that matters. Finally the last time I checked all the plugs I also took out the board batter for a few minutes to try and "reset" things. Not sure if that matters, either.

So, I'm at a loss where to go from here. I could replace the power supply, and I have read it could be a board issue, but I don't know why it would still power up occasionally?

Any thoughts would be fabulous. I need my computer for all 3! jobs and it's creating a huge problem for me.

Thanks!!