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I recently purchased a 1 TB Seagate ST31000528AS drive and I have Windows 7 RC (build 7100 installed on it). I've noticed that whenever the computer is idling, the hard drive light tends to blink at a rate of about once per second. What are the possible reasons for this?

As far as I can tell there should be no disk activity (all non-essential services are switched off and if there's some amount of swapping going on, then I would assume the drive activity would be a little more erratic that that.

At the same time I've installed drive activity monitoring software but it doesn't blink at the rate of 1 per second. So I'm inclined to believe that there's really no read-write activity taking place.

Bottom line..what's with the blinking lights?

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marked as duplicate by Kevin Panko, Journeyman Geek, James, Raystafarian, mpy Dec 14 '13 at 14:47

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Also I should mention that this is the only drive connected, so its not like there are other drives contributing to the blinking activity. – kpax Oct 10 '09 at 3:28

While this doesn't pertain to your exact drive model, this Seagate knowledge base article implies that a slowly blinking light means the drive is in power save mode. This would make sense in your case, especially if you are seeing this during idle periods and no activity in the activity monitor.

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Well, I'm using the computer now (so its not in power save) and the drive's still doing the 1-blink-per-second thing. Interesting. – kpax Oct 10 '09 at 3:26
I always liked the symbolism of blinking! to show that something is in save!! mode. – Rook Oct 10 '09 at 3:54

There is a possibility that the problem is not your hard drive, but rather a SATA DVD / CD / Blu Ray drive. What is happening is that Windows continually pings the drive about once per second to see if there is any media in the drive so that it can start Autorun. You can test this by going into your device manager and disabling your CD drive. Disabling Autorun will also cause the light to stop blinking. For practicality sake, you'll probably just have to live with it.

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This could also be due to Indexing pre-fetching and the like. If you would like to see exactly whats writing to the disk you can also use a program like Process Monitor.

Didn't notice the non essential services switched off part. The process monitor may still help though.

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You can check if it's something like this here -- a service which is supposed to support the driver but written so badly that it polls once per second:

Why does my hard drive LED light blink every second?

In case you have a service named "Broadcom Card Reader Service" it's certainly the real case of unnecessary blinking, just disable it and the blinking will go away. If you don't have it, you'll have to investigate more. As I've documented, sometimes it's not so obvious which poorly written program is the cause.

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Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. – Canadian Luke Dec 12 '13 at 22:43

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