You shouldn't activate the pc without the cooler in full operation. And you shouldn't switch on the pc without having tested your wc loop for leaks.
Not straightforward because ideally you'd need a 2nd power supply & some sort of molex to pwm power lead converter or hub to plug in the pump to test it.
I avoided all the issues of a built into the case custom loop with my design of custom loop which is a 12v dc pump on a seperate dc psu, in a reservoir (aka bucket of water) connected by 1.5m of tubing to the cpu block and radiator which is dangling from underneath a cupboard held up by string and hooks, in other words, my pump and reservoir are situated outside the pc case, and I tested the entire assembly for leaks, for a week in a sink, prior to installing the cpu block on the cpu. My radiator is not a standard pc water cooling radiator. It's a motor transmission cooler.
So you might have got some drips from the vrm water block that caused a short, before the major leak, but nothing seemed to go flash or bang, but components can also die slowly after being shorted rather than instantly.
Pins bent in socket, plastic burning smell well the cpu certainly warmed up without the cooler being operational, the only way to find out if things are still working is to dry out the system, thoroughly so that means, disassemble the pc, take out the board, inspect for moisture, let it rest for 12 hours, and make really sure the water loop is water tight, and test it by switching it on from a different psu and having the pump plugged into a pwm hub powered off the 2nd power supply, so that no power is going through the PC power supply & motherboard while you are testing it, you should test the loop for leaks separately with the pc totally powered off.
Might all have been a near miss but I haven't seen anything that definitively says anything fried, the burny plastic smell is like ozone
Ozone has a distinctive
smell that humans can detect even in small concentrations — as few as 10 parts per billion. Here are some of the ways the
smell of
ozone is described: Metallic. Like a
burning wire.
That could be simply because when the cpu warmed up the socket some volatile chemical compounds evaporated from the material of the printed circuit board that is the mobo but nothing necessarily 'melted'. Ozone has a strong odor. You should however inspect the board for anything that looks burned in the cpu socket / vrm area. Can't say for sure either way but it would have been preferable not to overheat the cpu.
Just be careful when you reassemble the system and test the water loop with the pc components powered off, in future. You will need to buy that separate molex to
pwm hub or
lead so you can power the pump from a second psu, situated outside the case not near where water can spill, standing on some books so that any water spills don't run over the table into it, you get the idea, don't power the pc until the leaks are definitively not leaking and won't ever leak. You can switch on the 2nd psu with a paper clip which is inserted into 1) the green wire and 2) an adjacent black wire, or else, you can get some sort of plug thingy or micro switch to simulate an 'on button'.
For example.
You could also for example, use some pvc pipe glue where you connect the pipe to the compression couplers, which is one more layer of drip prevention, though nobody really does that with their compression couplers, but doesn't mean that you couldn't if it was worrying you. Glue isn't all that convenient for couplers that will some day be undone anyway that's something optional but not strictly necessary. Tubing of the correct size in the same size couplers will not drip, tubing mismatched to the coupler size leaks.
Some varieties of compression coupler can leak, such as elbow couplers in this
video. The main point to stress again, 'test for leaks separately from the pc, don't turn on the water cooling loop and the pc at the same time, the first time, and well read around for any issues known to affect the hardware you're using. Not many people would've guessed the join in the elbow coupler would leak with a bit of lateral pressure. Be totally careful.