[SOLVED] Internal SATA HDD slower than external HD enclodure

[henrypam]

I have Dell XPS8930 Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz 3.19 GHz, 32 RAM, Windows 10.
I installed 2 internal HDD: WD Black 5TB, and Toshiba 4TB.
When I performed CrystalDiskMark, both of my HDD speed of R/W are about 150MB/s.
But when I plug another Toshiba 2TB HD into an external Plugable enclosure via USB, the CDM test show R/W at 200MB/s.
My IDE controller is Intel 300 SATA AHCI controller driver 17.9.6.1019
I thought that the internal HDD should have run faster than the external. What could be the problem? Thanks for any advise.

 

[Lutfij]

Perhaps you'd be best served if you could inform what the chipset on your motherboard is. As s side note, does your Dell XPS have an SSD on it as well? i'm asking to figure out f the larger capacity drives you've listed above are partitioned and have other tasks entrusted to them. A side note is that a 2TB drive will have less surface area than the 4TB and 5TB. To also add, you've simply mention the brand and their drive capacity(only exception of mentioning the color of the drive. Is it possible to state what the RPM of (all)said hard disk drives are?

 

[fzabkar]

You could use HD Tune to get a read benchmark graph. That should show whether the performance has a plateau. A transfer rate of 150MBps is what you would expect from a 1.5 Gbps SATA connection.

 

[henrypam]

All HD drives are 7200 RPM.
There are 3 internal SSD drives:
- Samsung 860 EVO houses Windows 10 OS.
-Samsung 970 EVO 1TB- photos
-Samsung 970 EVO Plus 2TB- photos.

 

[henrypam]

I removed he 4TB internal HD and inserted it in the Plugable enclosure, the CDM test showed R/W 150 MB/s consistent with the result when it was internal.
Possible conclusion: smaller HD with less data seems to run faster than larger HD with more data. The 2TB HD has 15% data, the 5TB and 4TB have 90%.

 

[fzabkar]

I removed he 4TB internal HD and inserted it in the Plugable enclosure, the CDM test showed R/W 150 MB/s consistent with the result when it was internal.
Possible conclusion: smaller HD with less data seems to run faster than larger HD with more data. The 2TB HD has 15% data, the 5TB and 4TB have 90%.

The data transfer rate depends on the data density (TB per platter) and rotation rate (7200 RPM or 5400RPM).

If you gave us the actual model numbers, then we could consult the datasheets. As it is, a capacity on its own tells us nothing. For example, your 4TB drive might have 2 x 2TB platters or 4 x 1TB platters. The performance difference would be about 40%.

As I said before, a HD Tune read benchmark graph will tell you everything, even the number of heads.

How to determine number of heads using HD Tune:
http://www.hddoracle.com/viewtopic.php?f=59&t=650

Another way to determine the data density, at least for a WD drive, is to consult WD's warranty checker:

https://support.wdc.com/warranty/warrantystatus.aspx

This will tell you the number of heads.

 

[Bob.B]

I removed he 4TB internal HD and inserted it in the Plugable enclosure, the CDM test showed R/W 150 MB/s consistent with the result when it was internal.
Possible conclusion: smaller HD with less data seems to run faster than larger HD with more data. The 2TB HD has 15% data, the 5TB and 4TB have 90%.

Wonder if this has something to do with fragmentation.
The larger hdd's show ample space to run the speed test but that space may be in little chunks all over the pack.
The result is the speed test is jumping around to multiple little chunks of the pack.

Where the speed test on the smaller hdd just uses one big chunk.