Every 10°C hotter makes a hard drive about 23% more likely to fail, and I make sure my NAS fans work now

Published Sep 29, 2026, 1:01 PM EDT Maker, meme-r, and unabashed geek, Joe has been writing about technology since starting his career in 2018 at KnowTechie. He's covered everything from Apple to apps and crowdfunding and loves getting to the bottom of complicated topics. In that time, he's also written for SlashGear and numerous corporate clients before finding his home at XDA in the spring of 2023. He was the kid who took apart every toy to see how it worked, even if it didn't exactly go back together afterward. That's given him a solid background for explaining how complex systems work together, and he promises he's gotten better at the putting things back together stage since then. I've run a Synology NAS for years, and I'll admit I treated its cooling the way most people treat a smoke detector. It was there, it probably worked, and I never looked at it. Then a peer-reviewed study of more than 443,000 hard drives found that every 10°C of extra heat was tied to roughly a 23% higher failure rate, and we covered what it says about drive brands here at XDA. So I opened up my NAS. Even the best NAS devices rely on a couple of small fans, and mine was set to Quiet mode with the inside coated in dust. DSM is the reason plenty of people still recommend Synology, but it never warned me about any of this. Here's why that matters, what to check on your own box, and what actually moved the numbers on mine. Why 10°C matters more than it sounds A 443,000-drive study did the math Credit: Source: XDA Economists Christoph Siemroth of the University of Essex and Yeomyung Park of Sungkyunkwan University went through 12 years of Backblaze's public drive data, covering 443,156 drives and more than 1.66 million drive-years. After controlling for age, capacity, and brand, they found that each additional degree Celsius in average drive temperature increased the failure rate by 2.1%. Compound that over 10 degrees, and you get about 23%. That's a relative figure, not a coin flip. The authors' own example is a drive with a 2% annual failure rate at 40°C, which would drop to about 1.6% if you cooled it by 10°C. Sure, that sounds small for one drive, but a NAS holds several drives with all your data on them, and the odds stack up across every bay. To be clear, this is an association in data-center drives, not a lab experiment. The researchers note that Backblaze runs enterprise drives under controlled conditions, so the results may not translate directly to consumer hardware. Older research is also mixed: Google's 2007 study of 100,000 drives found that cooler drives actually failed more often, and a 2014 Backblaze survey found no correlation at all. But the manufacturers aren't hedging. Seagate rates the Exos X20 drives in my NAS from 5°C to 60°C, and its IronWolf Pro manual explicitly states that it doesn't recommend sustained case temperatures above 60°C because running hotter shortens the drive's life. So the question isn't whether heat matters. It's whether your NAS is quietly adding 10°C you didn't know about. UGREEN DXP4800 Pro $720 $800 Save $80 Ugreen has been smashing it with powerful NAS units, and this is no exception. Memory 8GB (expandable to 96GB) What to check on your own NAS Start with the numbers DSM already shows you Every drive reports its own temperature, and DSM puts it right in front of you. Open Storage Manager -> HDD/SSD, and each drive lists its current reading. Anything in the 30s to low 40s (°C) is comfortable, while drives that sit in the high 40s or 50s all day are the ones the study is talking about. Don't just look at the average. Compare bays, because a drive running 6–8°C hotter than its neighbor points to an airflow problem, not a bad disk. Drives sandwiched between other drives run a little warmer, which is normal, so watch the hottest bay rather than the coolest. Next, check the fan setting under Control Panel -> Info Center -> General. DSM offers Full-Speed, Cool, Quiet, and, on some models, Low-Power modes, and Synology's own description admits that Quiet mode may let temperatures rise. Mine was on Quiet. I don't have a good excuse for that. I mean, I sit next to it, and those fans are loud when they ramp up, which is a reason, but it's no excuse for hampering the cooling performance. Look for the problems DSM won't flag A current reading only tells you about right now. Each drive also stores its lifetime temperature range, which shows whether a past fan failure or a heat wave pushed it close to the limit. If you have SSH enabled, run this and swap in your own drive's device name: sudo smartctl -l scttempsts /dev/sde Then there's the stuff no dashboard shows. A failed fan makes a Synology NAS beep, but dust builds up silently, and a clogged intake can make a fan work harder while moving less air. The only way to know is to look inside, so power it down and pull a drive tray. How I cooled my NAS back down Dust, fan mode, and one variable I didn't expect My DS1621xs+ currently holds two Seagate Exos X20 20TB drives in bays five and six, with just over 21,600 power-on hours each. With the room at 74°F, Quiet mode, and a lot of dust, they read 38°C and 40°C. That's nowhere near dangerous, but it's warmer than it needed to be. So I carried the NAS outside and blasted it clean with a DataVac, fans, trays, backplane, and all. Then I switched the fan mode to Cool and let it settle for a few hours at the same 74°F. The drives came back at 36°C and 37°C, a 2–3°C drop that the study's model ties to about 4–6% lower failure risk. Here's the part that surprised me. Earlier in the evening, with the air conditioning running, the same drives read 28°C and 29°C. Turning the AC off raised the temperature by 8–9°C, three times as much as cleaning and fan mode together. Condition Room Drive 5 Drive 6 Quiet mode, dusty 74°F 38°C 40°C Cool mode, cleaned, AC on Cooler 28°C 29°C Cool mode, cleaned 74°F 36°C 37°C That's the real lesson. A NAS in a warm closet, a summer without AC, or a dead fan can add 10°C without you ever noticing, and that's the exact scenario the study flagged. My drives were fine, but they were already a good way toward that 10°C from where they could be. The fixes that actually help These are the changes I'd make on any NAS, roughly in order of impact: Mind the room. Ambient temperature moved my drives more than anything else, so a cool, open spot beats a closed cabinet every time. Use Cool mode. It's slightly louder, but the fans ramp up before heat builds. Clean it. Blow out the intakes and fans every few months, and hold each fan blade still so compressed air doesn't overspin it. Keep every tray in. Empty trays are part of the air path, so a missing one lets air skip past your drives. Watch your spin-down settings. Hibernation saves power, but frequent heat-up and cool-down cycles are their own kind of wear. If you've already given Home Assistant access to your NAS, its Synology DSM integration exposes each drive's temperature, so you can set an alert for any drive above 50°C for half an hour. That catches a dead fan in hours instead of whenever you next open DSM. Your NAS fans are cheaper than your drives A NAS makes it easy to forget about the hardware, and that's usually the point. But fans clog, settings drift, and rooms heat up, and none of it announces itself until a drive starts throwing errors. The 443,000-drive study gives a number to what that neglect costs, and my own drives showed how easily 10°C can creep in from the room alone. So check your temperatures, check your fan mode, and look inside the box every few months. If your drives are sitting in the 40s on Quiet mode with a layer of dust, you now know what that might be costing you. Mine run a few degrees cooler now, and I'm not letting the dust come back.