Q & A : Benchmarks : Capacity vs. Power (aka Size Efficiency)

A chart, available in all benchmarks that compares the capacity of the device with its power (TDP). It allows us to view how capacity varies with power dissipated (and thus consumed) and how competing devices perform for the same amount of power (aka power envelope).

For storage devices (memory, hard disks, etc.) the primary metric is not performance but Size Efficiency, i.e. how much capacity you get for the power envelope available. In some cases, you have a limited amount of power (either to consume or to dissipate, aka "power envelope") and need to select the largest capacity within that power envelope.

1. The result is a ratio of capacity (GB, MB, etc) over power (TDP W, etc.)
2. As higher capacity is always better, the higher the ratio of capacity over power the better the Size Efficiency.

Testing various current desktop memory sub-systems or just checking out the reference results makes the differences in architectures and implementations very clear.

Rank	Chipset / Memory / Processor		Size / Power	Size Efficiency	Commentary
#4		AMD 870 / 2x 2GB DDR2 PC2-6400 / AMD Phenom X4 970	4GB : 12.5w+8.2W TDP (chipset+memory only)	193.2 MB/W	This AMD system only has an acceptable size efficiency because of the higher TDP of the chipset.
#5		AMD 890FX / 2x 2GB DDR3 PC2-10600 / AMD Phenom X6 1055	4GB : 19.6W+4.8W TDP (chipset+memory only)	163.9 MB/W	An enthusiast level chipset, but here comes the last due to a higher current comsuption.
#2		Intel H55 / 2x 2GB DDR3 PC3-8500 / Intel Core i3 550	4GB : 5.2W+4.08W TDP (chipset+memory only)	431.0 MB/W	Lower RAM frequency helps this system to be very good at size efficiency.
#3		Intel P55 / 2x 2GB DDR3 PC3-10600 / Intel Core i5 760	4GB : 4.7W+4.8W TDP (chipset+memory only)	421.1 MB/W	Despite having a good chipset TDP, this combination is in third place because of the higher DDR3 clock.
#1		Intel X58 / 3x 2GB DDR3 PC3-12800 / Intel Core i7 975	6GB : 28.6W+7.38W TDP (chipset+memory only)	542 MB/W	You may think that a bigger TDP or larger RAM can be a disadvantage, but here those are defining a clear winner.

You can check your own chipset/memory's Size Efficiency or view how other chipsets/memory measure up using the Capacity vs Power tab in Sandra's benchmarks.

Most Popular Hard Disks, Chipsets & Memories

Most popular Hard Disks as benchmarked by users (past 30 days):		Most popular Memory Modules as benchmarked by users (past 30 days):
1. 5% SAMSUNG HD103SJ 87.00 USD 2. 4% WD WD5000AAKX-001CA0 68.99 USD 3. 3% Seagate ST1000DM003-9YN162 89.00 USD 4. 3% OCZ-AGILITY3 349.99 USD 5. 3% Seagate ST31500341AS 216.00 USD		1. 3% 4GB Corsair CMZ8GX3M2A1600C9 DIMM DDR3 PC3-12800 45.99 USD 2. 3% 8GB Kingston KHX1600C9D34GX DIMM DDR3 PC3-12800 84.38 USD 3. 3% 8GB Corsair CMZ16GX3M4A1600C9 DIMM DDR3 PC3-12800 84.38 USD 4. 3% 8GB Kingston KHX1866C9D34GX DIMM DDR3 PC3-14900 84.38 USD 5. 3% 4GB G.Skill F3-12800CL9-4GBXL DIMM DDR3 PC3-12800 45.99 USD
For a complete list of statistics, check out the Most Popular Hardware page. For a list of more products, see SiSoftware Shopping.

Typical Results from Hard Disks on the Market

Testing various current hard disks or just checking out the reference results makes the differences in architectures and implementations very clear.

Rank	Disk		Size / Cost	Size Efficiency	Commentary
#2		WD Caviar Black SATA 7200 RPM	2TB : 10.7W TDP	186.9 GB/W	Surprinsingly this classic drive has a better efficiency than an SSD due to its huge storage capacity.
#4		LaCie Starck USB 2.0 External HDD	2TB : 24W TDP	83.3 GB/W	The USB controller makes this combination less efficent than a desktop drive with the same capacity.
#5		Seagate Cheetah SCSI320 15k RPM	300GB : 16.35W TDP	18.4 GB/W	This power hungry classic enterprise drive has unfortunately a very low efficiency index.
#6		Fujitsu MBA3300RC SAS 15k RPM	300GB : 18.34W TDP	16.4 GB/W	Having a latest generation interface didn't help this drive to be placed above the old SCSI.
#1		Intel X25-M SATA II MLC	160GB : 0.15W TDP	1066.7 GB/W	Easily the best size efficiency around when speaking of storage devices.
#3		Kingston SSDNow V+ SATA II MLC	256GB : 2.6W TDP	98.7 GB/W	A very good size efficiency given the fact that this storage tehcnology has no moving parts.

You can check your own disk's Size Efficiency or view how other disks measure up using the Capacity vs Power tab in Sandra's benchmarks.

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