I wish somebody had told you it was probably your battery before your power supply. I'm guessing your 751TM is ~5 years old because my 770zm is fixing to turn 8 years old in 2 months. My power supply works great and Clevo uses a good supplier for psu. it's probably your battery. it's old. I've been in latin america ~18 months and one of the things I didn't buy but was high on my list was a battery. At the time when I was still in the US I think XoticPC had a couple left and saw there were some on Amazon US for ~$65 and I was very hesitant because they usually cost at least $100 and I think originally it was $130USD. seeing your battery is acting up that bad, it kind of is a fire hazard. because of this, if you can't find a proper battery it may or may not be worth buying because I can't tell you that's a good chinese battery. at half the price and no reputation it's a gamble. but you and I both know the batteries for our laptops are more UPS and give us plenty of time to shutdown depending on situation and length of no power.
The last 3 years my 770 has been off a lot, for extended period of time and I often turned it off after using it. I let it run down off battery after I got to Mexico and it lasted about 30 minutes doing nothing with about 20% left. HWinfo was reading about 75% health last I was paying attention and would occasional read over 95%. If you don't want to buy that battery off amazon, I would try calling Sager and Clevo. I would guess that battery lived a few models, maybe including yours (I have 4790k) for both the 15" and 17". It's been so long since I kept up with the laptop scene I don't know what resellers are around. Check the UK and US and maybe other markets. There's bound to be one somewhere but how much?
