Windows 7: Is leaving your computer on all the time (24/7) better for hard drive?

Powering up is the most stressful activity a hard drive experiences.

I wouldn't disagree with that. Like most things, it depends on usage. If you save nearly every machine you ever bought and add it to your local network, then you may wish to leave everything up 24/7. I'm probably similar to most users in that I'm cramped for space. Usually the PC becomes obsolete before anything major malfunctions. I didn't even start saving drives until they reached 200 GB and I bought a few docking stations. For most people the thing will be discarded because it's too slow not inability to boot.

Because error messages occur only on power on, the proves power on is destructive? Yes, for many. Instead, view the system (event) logs. Same problems were being reported mostly when the computer was not power cycling.

So the question, "Is power cycling destructive?" One who said so only using speculation and subjective reasoning said yes. Instead, let's read numbers. For example, the worst drive I ever saw was rated for 40,000 power cycles. That means power cycling seven times every day (even on holidays) results in a failure after ... 15 years. So power cycling is destructive. And perspective (the numbers) says nobody cares.

Why did that friend not include numbers? A majority will recommend on hearsay, myths, wild speculation ... and no numbers. A typical drive is rated for about 100,000 power cycles. Again, seven power cycles every day (including holidays) for ... 39 years.

If the answer does not include numbers, then suspect a scam. Power cycling is a myth easily promoted by junk science reasoning - answers without perspective - without numbers.

Most defects are manufacturing defects. Completely unrelated to power cycling. View system (event) logs to see that most failures occurred during normal operation.

Learn how to separate hearsay from knowledge. Subjective claims are best classified as urban myths.

It should be fine. Ive helped a lot of people with computer issues, and going to school for electrical engineering. specifically in the area of computers. and ive never seen a harddrive fail.
To be honest with you todays computer hardware is generally very reliable.

I always turn off my PC and I never had any problems. But then it is only turned on about two-three times a day. So it is not much used, unlike some people.

When shopping for parts as i'm good as i'm doing for food!!!

Looking at the lastest date it'll have to be consumed, if the package is well sealed, how it looks and how well reputated it is...will it be that sweety for my taste, and so on.

It happens i do also eat some "junk food" for my best!

I perfectly know that i will eat all that within the ten days.

But i'm never safe from dropping my dinner or burn all that, discussing on Sevenforums.

Most errors comes from me and sometimes related to Brands hiding perhaps some specs that can't handle some enhancements through the O.S.

Mine gets turned on a max once a day. Same for powering off. There's absolutely no reason for my computers to be running when I'm asleep, so at night they get shut down. If I am home during the weekend, and I turn it on, I will leave it on during the day, in case I will use it again.

Power-cycling many times a day will surely reduce the life of a drive. Once a day or so, is definitely not hurting the drives. Think of it like a car. Turning it on and driving it somewhere, then turning it off, isn't bad for the car. Doing it 10 times a day...is bad for the car.

Hybrids restart the gas motor many times a day.

Most HDDs I know if left idle for a while stop spinning at least and some even park their reading heads (depending on how it's set in power management and/or make/model), going to "sleep" state.

The difference between this and being shut down is minimal. I frequently abuse my hardware and software (hard shutdowns, weird programs and stuff), but never dropped a HDD, and in 5-6 years over multiple machines no HDD failed. I have a couple that acted weird since the beginning (even if I couldn't find any issue with them), but closed in an external enclosure they ran fine.

Since you seem to be killing HDDs at an unreasonable rate, I suspect there is some fault in your mobo. Post the errors you are getting and maybe someone can help find the culprit.

More for the car battery than for the engine itself.

That's the way I do it. On in the morning, off at night. Only time I power completely down is due to an electrical storm. The land is very flat where I live. Even with UPS/surge box it's safer to power down during the lightning strikes.

Afa the energy saver drive spin down/spin up every 10 minutes. I never liked that idea. Just the inertia of spinning up a stationary platter has to produce some stress. At some point SSD will be the norm. We'll have a different argument then.