HP Z230 with i5-250 CPU and 32Mb of Dram3 just recently upgraded OS from Win 7 to 10 last week. Hello HP experts, No issues since new Win 10 OS installed last week. I was a happy camper until Today the PC “froze” in middle of Photoshop edits.( I do not use the PC for gaming.) Hoped a forced restart would fix the freeze. Now the device does not post; followed by a high speed (power supply?) fan 40 seconds after switching power on. No excessive heat detectable anywhere. I have swapped the power supply cable and reseated the 4 memory cards to no avail. Your suggestions appreciated.