When running a hardware RAID card, you really do need to be running a proper UPS (not all are the same). The reason for this, is that even with a battery backup unit attached to the card (aka BBU), if the data being saved is greater than the cache, you get a corrupted write anyway (= re-perform work). Another issue with a BBU is if it can't maintain the data long enough to get power restored (usually only an issue if the battery is weak or it's an extended power outage, such as a major disaster like a flood, hurricane, ...).
But by having a UPS, it reduces this (can still happen if the write will take longer than the UPS batteries can run the system,
and the BBU won't cover the balance <remaining capacity is still greater than the cache, or it's power dies before power is restored>).
So the moral of the story is, get a good UPS...
Some examples (US models BTW, but there are international versions available):
BTW, the APC branded units can be had as refurbished models, and work just fine (make sure the electronics function properly and install a new set of batteries). The CyberPower unit is probably too new to find refurbished, but they're not expensive.
Cost wise, the APC units are more expensive new, but refurbished will put them much closer to the CyberPower model <new> (there are some differences in the inverter types, but both will work with Active PFC based PSU's, which is what the MP uses and why you need to get the right model). Examples seemed easier than trying to explain every detail, but if you look closely at the Technical Details pages vs. cheaper units, you should see it (hint: inverter type; stepped inverters = damage A-PFC based PSU's.
- Now in terms of the temp, interrobang makes a good point; so what is the basement's temp when you're turning the MP ON?
If it's colder than the specified operating conditions (also pay attention to humidity values), then he's right that you need to warm the room up. Or move it to a heated room and deal with the noise (MP isn't that loud; trust me, if you've listened to rack mount systems, you'll know what loud is

).