Battery Backup Late 2013 w/SSD + SSDs And Power Failure?


macrumors newbie
Original poster
Dec 31, 2013
What I paid for my new iMac is, for me, a lot of money. I got most of the add ons: i7, 780M 4mb, 16mb ram, 1TB SSD. I have a regular APC 750 battery backup & I was going to use that on my iMac. However, I have been reading that SSDs can be severely damaged by power failure. I have also read that they need pure sine wave power and "smart" battery backups.

Is it true that SSDs can be significantly damaged by power outage? What exactly is the difference between pure sine wave and other forms of power? What does a Smart Battery Backup give you that a non-smart doesn't?

Finally, what would you recommend? I don't want to skimp on this since I paid so much for the iMac. On the other hand, I don't want to buy protection I don't need. I was hoping to spend $200 or less... if necessary I would spend more. It would be foolish not to spend more if needed.


macrumors member
Jan 1, 2012
St. Lucia, West Indies
As far as I am aware just about any computer power supply won't really know the difference between a modified sine wave (the type of output from the vast majority of UPS's) and a pure sine wave (your mains and some more expensive UPS's).

You have to remember that all the power supply is doing is converting the incoming AC to various DC voltages and there are filters installed to ensure that the output is both stable and lacking in spikes. Your SSD will not care as long as the DC voltage it receives is stable.

I think your APC 750 will be more than enough to provide adequate backup time and your iMac will be just fine.

If your UPS is more than a couple of years old, you might think about changing the battery as they do loose capacity and not give you the run time you expect.


macrumors 6502a
Apr 28, 2012
All electronic components (pretty much) can be damaged by power outage and I don't think SSD's are any worse than anything else in that regard. However, I suspect what's being referred to is the fact that if you have a power outage with a hard disk, you could lose a few sectors and a bit of data but you'd be very unikely to lose the whole drive. And even if you did, you could send it away to have really critical data recovered. Although unlikely it is conceivable that an SSD could stop working altogether after a power cut/spike and you could lose the lot.

Regards UPS's the word "Smart" is pretty meaningless. I think it originally meants UPS's that talked to the computer so it could shut the computer down etc. They all do that now, so the term is irrelevant. I don't think you can buy a dumb UPS.

And pure sine wave vs stepped sine wave? It depends on the power supply in the computer. Some power supplies really hate - or will not work at all - with a stepped sine wave input. I bought a pure sine wave UPS because of fears over this, but from what I can gather, the iMac's will tolerate stepped sine wave for the few minutes they might be exposed to it. There's lots of people using stepped sine wave UPS's with iMacs with no issues.

Whether you go for pure sine wave or stepped sine wave has no bearing at all on the likelihood of SSD damage. The SSD only "sees" the output from the iMac's PSU - it can't tell what sort of UPS is on the other side.


macrumors 604
Apr 6, 2007
All electronic components (pretty much) can be damaged by power outage and I don't think SSD's are any worse than anything else in that regard.

This. The risks of damage to electronics from power outages has been around long before SSDs have started hitting the market. There's nothing about an SSD that is more or less susceptible. The main thing you have to be concerned about are under voltages (brown outs) and over voltages (spikes) that can occur before and after an outage. A good surge suppressor or UPS will handle these reasonably well and lower the risk of damage.

Anyway, I've had a little experience with SSDs. At work we have a dozen or so 27" iMacs with SSDs, a dozen more with Fusion Drives, and I have a couple of SSDs in USB enclosures. All of the iMacs are on MSW UPS units. Only one has had a failure, and it was a Fusion Drive model (and the hard drive portion, at that). I've also seen a few SSDs in external enclosures get unplugged "unsafely" and they were fine.
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