Yesterday night, I shut down my system (i.e. desktop pc) normally, and went to do whatever I needed to do. Also, I temporarily overclocked (just for testing purpose, as usually I do not OC) HD 5770 (GPU @ 900 Mhz, and Memory @ 1300Mhz), it worked perfectly without any issue beside these not that much of aggressive OCing, I ran couple of games without any issue for an hour I think, then restored the clocks to original settings (i.e. 850 MHz for GPU, and 1200 MHz for memory); and continued using the PC for a while without any issue at all. The system Specs for this machine are: 1. Core 2 Quad 8400 2. Intel DP35DP Motherboard (with BIOS updated to last released version) 2. 6GB DDR2 (Kingston) 3. 500GB WD Caviar HDD + 200GB Seagate Barracuda HDD 4. HP DVD/RW+ & LG DVD Reader 5. Radeon HD 5770 1GB 6. 19" Viewsonic LCD Monitor (@1680x1050) When I tried to turn on the system few hours later; it would turn on and a cursor would just blink on the left edge of the screen. No beeping, nothing except all three keyboard lights were on (stuck as well couldn't turn them off). Anyway, I first disconnected HDDs + DVDs, reduced the RAM to only one module of 2GB, nothing showed up at all. Changed the graphic card (have an old 7600GT lying around) nothing at all, and I know the card is fine as it works fine in the other machine. I disassembled the pc, brought out the motherboard to see whether something may be shorting out, again nothing. Checked the PSU, it works fine on the other pc with E6300 + 9600GT, similar 2 HDDs and DVDs, no issue it was fine. The long of and the short of it, as last resort I pulled out the motherboard battery, left the motherboard alone for the night, this morning i placed the original graphic card back on after putting the battery back in, and viola, everything worked just fine. Now, I have reassembled the pc, everything is back where it was, and everything is working just fine, infact I am writing this thread from this same machine. My question is, what could have caused this? and how? and why there wasn't any beep? Edit: I just went through Event Log of the motherboard's BIOS, and it has two recent errors: i. Intel ME Interface Non-Functional ii. Intel ME Interface Initialization Failed As far as I know, Management Engine is the interface between the firmware and the host. The same is backed up by Intel as Drivers and applications on the host that wish to interact with Intel ME through host interface would use the ME Interface host windows driver. So the scope has somewhat narrowed, and the thing is what caused it to become 'Non-functional' & its 'Initialization Failed', and how it ended up fully functional again, considering the scenario I described above.