Aurora R4, start with only one side panel?

Absolutely I can power on my R4 with left panel open.  Np at all.

however a room vent blowing cold air on the hot cpu is not going to work too well.  Yes you can cool it down a little bit only.  I would try to use another pc for work while waiting for a replacement cooler.  It is not worth risking damage to the R4 cpu causing early demise.

the cpu has a very small area of heat spreader (IHS) on top of the actual cpu die.  The function of air cooler heatsink is to conduct heat from IHS to a much larger surface area and then blow air across it to dissipate.  Therefore if you try to blow cold air onto the cpu IHS alone, it is highly ineffective to cool it.  The rate of heat generated far exceeds the ability of fan to remove it.  The x79 LGA2011 cpu has a high TDP of 130-150w which makes it even more difficult to cool without an efficient cooler.

I would not recommend using it until you get the cooling solution working. A fan will not be able to cool the CPU properly because the water cooled pump block is not designed for air flow cooling and blowing air on it will do very little to nothing.

110 is way to high and will likely end up damaging the CPU. Not worth it in my opinion.

Yes, the Aurora-R4 will run without the side-panel installed ... but NOT with a malfunctioning Liquid-Cooler.

I agree with both @redxps630 and @Vanadiel  . 

Better to keep it turned off. For now, use your old computer or laptop or maybe your phone/tablet.

The proportion between AIR vs DIRECT CONTACT is somewhere around 40 times the thermal efficiency...

Thanks for all your fast answers, I really needed these opinions/facts. So I'll wait for my new watercooler and use my phone.

A wise decision, indeed.