> I am thinking about replacing the hdd of someone I know by a ssd.
> Ik know the ssd must not be too thick but are there other things that
> matter and to whom I should pay attention?
If you buy a 550MB/sec SSD, it won't get the full speed from a
300MB/sec laptop SATA interface. This does not affect the operation
at all, just your expectations of the speed should be reduced.
SSD drives draw different amounts of DC power. A hard drive, might
use about 2 watts during read/write. Some of the early SSD drives
used higher power levels. This is an issue if the hard drive bay
in your laptop, normally gets hot. (This has even been a problem
in the past, with replacing a 5400 RPM HDD with a 7200 RPM HDD.
Some of those would overheat, because the cooling was so poor.)
To give an example: http://www.newegg.com/Product/Produc...82E16820233227
Power Consumption (Idle) 0.4W
Power Consumption (Active) 7.3W
Now, such an SSD drive might not spend much time doing read/write, so
you could argue the time spent in the 7.3W state is minuscule. But
the drives also re-arrange data internally, when they're not busy
doing other things. Which can consume some power. If a drive has
been abused by doing a random 4K write test, it might take
half the night for the drive to re-arrange data internally.
Now, we compare to another SSD drive. http://www.newegg.com/Product/Produc...82E16820147164
Power Consumption (Idle) 0.08W
Power Consumption (Active) 0.12W
Those values are unbelievably good. Should we trust such a declaration ?
If the SSD had eight channels internally, and 8 flash chips doing write
or erase at the same time, would the total power be only 0.12W ?
If I pick a laptop HDD at random:
WD Scorpio Black 250 GB SATA Hard Drives ( WD2500BEKT) http://www.wdc.com/en/products/products.aspx?id=790
Read/Write 2.50 Watts
Idle 0.85 Watts
Standby 0.25 Watts
Sleep 0.15 Watts
That's to give some idea what the laptop would normally have in it.