Average Bench: 39.3% (526th of 1015)

more Based on 4,515 user benchmarks.  Models: WDC WD6400AACS-00G8B1, WDC WD64 00AACS-00M3B, WDC WD6400AACS-00G8B0, WDC WD6400AACS-0, WDC WD6400AACS-00M3B, WDC WD64 00AACS-32D6B, WDC WD6400AACS-00D6B1, WDC WD64 00AACS-00M3B0, WDC WD6400AACS-00A7B2, WDC WD6400AACS-00G8B, WDC WD6400AACS-00D6B, WDC WD64 00AACS-00G8B, WDC WD64 00AACS-00G8B0, WDC WD6400AACS-32D6B1, WDC WD64 00AACS-00D6B, WDC WD64 00AACS-00G8B1, WDC WD64 00AACS-00D6B1, WDC WD6400AACS-00M3B0

Poor average bench

The WD WD6400AACS-00G8B1 640GB averaged 60.6% lower than the peak scores attained by the group leaders. This isn't a great result which indicates that there are much faster alternatives on the comparison list.


Avg. 4K Random Mixed IO Speed 0.75MB/s
Avg. 4K Random Write Speed 2.14MB/s

Good consistency

The range of scores (95th - 5th percentile) for the WD WD6400AACS-00G8B1 640GB is 22.8%. This is a relatively narrow range which indicates that the WD WD6400AACS-00G8B1 640GB performs reasonably consistently under varying real world conditions.


Avg. Sequential Mixed IO Speed 48.2MB/s
Avg. Sustained Write Speed 66.4MB/s

Average Bench

(Based on 4,515 samples)
Min Avg Max
41.8 Read 70.1 89
41 Write 68.2 87
29.1 Mixed 48.2 58.5
36.5 SusWrite 66.4 85.2
46.6% 63.2 MB/s
Min Avg Max
0.3 4K Read 0.54 0.6
1.2 4K Write 2.14 2.6
0.5 4K Mixed 0.75 0.9
145% 1.14 MB/s
User Benchmarks Bench Sequential Random 4k Deep queue 4k
The fastest HDD (mainstream) averages a speed of 100%
229GB free
Firmware: 01.00A01
SusWrite @10s intervals: 74 78 78 78 79 79 MB/s
Read 99.3
Write 95.7
Mixed 66.7
SusWrite 77.5
63% 84.8 MB/s
4K Read 0.7
4K Write 2.2
4K Mixed 0.9
170% 1.27 MB/s
596GB free
Firmware: 05.04C05
SusWrite @10s intervals: 77 80 81 82 60 76 MB/s
Read 79.1
Write 79.5
Mixed 55.3
SusWrite 76
53% 72.5 MB/s
4K Read 0.6
4K Write 2.1
4K Mixed 0.9
164% 1.2 MB/s
562GB free (System drive)
Firmware: 05.04C05
SusWrite @10s intervals: 64 69 66 63 59 68 MB/s
Read 82.2
Write 66
Mixed 42.7
SusWrite 64.7
47% 63.9 MB/s
4K Read 0.6
4K Write 2.3
4K Mixed 0.8
156% 1.23 MB/s
227GB free
Firmware: 05.04C05
SusWrite @10s intervals: 58 54 58 57 60 58 MB/s
Read 64
Write 53
Mixed 46.5
SusWrite 57.5
41% 55.2 MB/s
4K Read 0.5
4K Write 2.2
4K Mixed 0.9
162% 1.2 MB/s
4,515 MORE »

 Market Share (See Leaders)

The number of benchmark samples for this model as a percentage of all 23,217,153 HDDs tested.

Typical WD6400AACS-00G8B1 640GB Builds (Compare 131 builds) See popular component choices, score breakdowns and rankings.
Gaming 11%
Tree trunk
Desktop 30%
Workstation 15%
Tree trunk

System: Medionpc MS-7501

EDIT WITH CUSTOM PC BUILDER Value: 20% - Very poor Total price: $325

Popular WD6400AACS-00G8B1 640GB systems:

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Welcome to our freeware PC speed test tool. UserBenchmark will test your PC and compare the results to other users with the same components. You can quickly size up your PC, identify hardware problems and explore the best upgrades.

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How it works

  • - Download and run UserBenchMark.
  • - CPU tests include: integer, floating and string.
  • - GPU tests include: six 3D game simulations.
  • - Drive tests include: read, write, sustained write and mixed IO.
  • - RAM tests include: single/multi core bandwidth and latency.
  • - Reports are generated and presented on userbenchmark.com.
  • - Identify the strongest components in your PC.
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Hard Drive Rankings (Price vs Performance) January 2020 HDD Rankings.

We calculate effective speed which measures performance for typical consumers. Effective speed is adjusted by current cost per GB to yield value for money. Our calculated values are checked against thousands of individual user ratings. The customizable table below combines these factors to bring you the definitive list of top HDDs. [HDrivePro]


Group Test Results

  • Best user rated - User sentiment trumps benchmarks for this comparison.
  • Best value for money - Value for money is based on real world performance.
  • Fastest real world speed - Real World Speed measures performance for typical consumers.


1015 Drives (Compared) Thousands of user benchmarks compiled into one comparison list.

See how consistently different HDDs perform with varying real world conditions. The charts also illustrate overall performance, popularity and rank.

 Frequently Asked Questions

 Best User Rated

The Best.
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Intel Core i5-9400F $155Nvidia GTX 1650S (Super) $160Samsung 850 Evo 120GB $78
Intel Core i7-9700K $370Nvidia RTX 2060 $339Samsung 850 Pro 512GB $204
Seagate Barracuda 1TB (2016) $37Corsair Vengeance LPX DDR4 3200 C16 2x8GB $80SanDisk Extreme 64GB $72
WD Blue 1TB (2012) $35Corsair Vengeance LPX DDR4 3000 C15 2x8GB $63SanDisk Extreme 32GB $46
Seagate Barracuda 3TB (2016) $85G.SKILL Trident Z DDR4 3200 C14 4x16GB $643SanDisk Ultra Fit 32GB $16
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