You may have missed an additional heat source when you opened her up to replace the thermal paste, or maybe the heatsink is not seated firmly on the CPU die. Another possibility is that the fan is on it’s way out, or that the sustained heat from before the repair has destabilized or damaged the CPU. I would: 1. open it up, check all the thermal grease/thermal pads (like the ones you find on memory chips in computer graphics cards). 2. reseat all of the heatsinks. 3. check to make sure there are no air obstructions in the intake or outtake air ports. 4. check all the power cables to the fans. 5. Check all the soldering points and reflow where necessary with a heat gun or a soldering iron. Hope this helps.
Turns out there is a ribbon connecting the SATA daughter-board and the motherboard on the Asus R556 series laptops which is faulty. There are two fixes; reflow the traces at both ends of the ribbon (it’s easy to identify, as it crosses the HDD caddy), or purchase a new ribbon, daughter board and ribbon connector (for the motherboard interface). Personally, I am inclined to agree with you, ‘Planned Self-Termination’. :/ ….and Asus used to be so good too. :(
Same issue here. Bought a replacement hard drive for this laptop and it will not show the drive after the first time I booted the device to install windows. This is the third hard drive I have tried in this machine and each time it’s the same issue; works for a short period of time and then the drive stops being recognized by the system at all. I have cleaned the connections, tried a reflow of the daughter-board which has the SATA connector (and the motherboard too). Then tied a new HDD… NOPE. Fails within 30 minutes of the install. Bottom line is this is a very poorly constructed laptop with poorly engineered parts. This was supposed to be an easy refurb for a friend, and it’s just turned out to be a money pit. I do not recommend the Asus R5XX model line, and will be going back to Toshiba.