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2.5" 7200rpm vs 3.5" 5400rpm

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August 15, 2012 12:53:40 PM

Hello All,
I'm curious, would a 2.5" 7200rpm hdd have better read/write than a 3.5" 5400rpm? I know the 3.5" is a WD Green, not sure what the 2.5" is yet (I'll be removing it from a laptop I'm purchasing and throwing in an ssd). Was just curious, thanks!

More about : 7200rpm 5400rpm

August 15, 2012 8:03:23 PM

All other things being equal, probably.
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August 15, 2012 8:13:35 PM

I just know that the platter densities make a big difference, cache, and then the fact that laptop drives are made with much higher power efficiency standards in mind, so that's what confuses me...
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a c 288 G Storage
August 16, 2012 10:16:36 AM

Your question is indeterminate because we have no idea of the respective data densities (number of bits per square inch).

That said, if we assume that the two drives have exactly the same density, then the speed factor would favour the 2.5" drive. However, the 2.5" platter has smaller track size (bits per track) than the 3.5" drive, so this would favour the latter.

If we combine these two competing factors we get ...

(data rate A) / (data rate B) = (7200 / 5400) x (2.5 / 3.5) = 0.952

Therefore the laptop drive would be about 5% slower.

Of course the above exercise is purely theoretical.
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August 16, 2012 1:43:27 PM

My question IS infact determinate. You would be referring to the supporting information that I provided in response to oneblackened, which is indeterminate in the fact that I don't know the platter densities... which I made known that I didn't know the details of. So I suggest that if you say anything about my question's form, you say it accurately. I appreciate your efforts in trying to answer my question though :)  Basic logic would tell us that laptops have a higher density, if containing the same number of platters, but there may be a reason that my assumption is wrong, idk...
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August 16, 2012 1:51:13 PM

the densities assumption is based upon an equal capacity of course...
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August 16, 2012 1:56:37 PM

I really dont think you want to put a laptop drive into a desktop. If you want speed you should invest in a SSD.
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August 16, 2012 2:08:42 PM

I understand that, it's easy to say, but when you don't have the money at the time and you have both sitting in your possession then that doesn't help my present situation... I'm a firm believer in making the best with what you have until you can "change what you have." :)  As I originally stated in my first post, I am getting an SSD for the laptop, so the 7200 drive will be going into the desktop either way, rather than just laying around, so back to my original question.... which is likely to have a higher read/write speed? I say likely because I don't have the model number of the laptop drive yet... everyone is quick to shout get an ssd, but it's not actually answering my question.
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a b G Storage
August 16, 2012 4:58:30 PM

The 7200rpm drive will have better read/write speeds regardless of it size.

Case and point WD raptor drives are all 2.5 inch drives with a heat sink that makes them 3.5 inch in size. They spin at 10000rpms and you don't see any 3.5 inch drives coming anywhere close to them in read/write speeds.
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August 16, 2012 5:04:36 PM

Thank you for answering my actual question, and thank you to all those who've tried :) 
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August 16, 2012 5:04:52 PM

Best answer selected by velocitydreamer.
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a b G Storage
August 16, 2012 6:08:39 PM

I will follow up by saying that there are obviously many other things that go into the overall speed of a HDD, many of them have been mentioned in this thread. But the most influential factor will always be the RPMs and possibly the age of the drive or the connections/technology that it uses.
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