Originally Posted by
BigLar
Some of the 'compatible' replacements apparently don't identify themselves correctly to the laptop, and the machine doesn't want to do anything.
Annoying, sometimes they stop recognizing genuine Dell too. Work around is to boot from battery, log in then connect the power supply, but YMMV.
Dell claims they downclock the CPU when they can't recognize the P/S to avoid causing damage to the power brick. It seems they mean downclock to 4.77Mhz. There is at least one report of software out there that turns this 'feature' off, but you have to be able to boot before the software can run.
Actual draw on an older Dell Precision with a 180W brick observed as 25W-40W via a Kill-A-Watt meter; system has a Samsung SSD w/write caching. It was not under an insane load. The laptop was unplugged and connected to the meter while already booted. Test for boot, resume or wake-up not done -- no data on peaks.