Marge said:
Hi,
want to add SATA dvd to daughters pd but power cable does not reach.
The pc has IDE molex standard but with SATA half way down the cable.
Read about adapters from molex(ICE) to SATA but have question. Inside
daughters PC there are 5 wires upto the SATA plug 2black,red,yellow &
orange- from the SATA plug onwards to the molex(IDE) there are only
the usual 4 2black, red,yellow.
What is the orange for on the SATA is it needed? as the adapters I
have seen from molex to SATA are only going to supply the usual 4 to
the SATA connector?
Sorry first time user of SATA so just wanted to check....
The pinout is described here. The SATA standard introduces an
extra voltage level, which is not currently used by hard
drives or by optical drives.
http://en.wikipedia.org/wiki/Sata
The SATA power connector is a sort of "wafer" design. The connector
was designed for "backplane" operation, as in big server computers
with a couple dozen drives housed in them. The SATA connector pair was
intended to make it easy to slide a drive into a rack, and the
power and data on the back of the drive, snap into matching connectors
on the server backplane. With SATA hotplug capability, the server
could have a drive change, without shutting down.
Operation of that connector on the desktop, seems to have been a
second thought. When used in desktop systems, the first generation
connectors were less than ideal. They fell off.
A second generation of connector design was needed, to add extra
security to the connection. Some data cables now, have a metal
clasp to hold the cable secure. And that stops the cables from
falling out, like the first generation ones did. (The two parts
of the connector have to be from the same generation to work well
in that case. The clasp needed a feature to latch to.)
The SATA power wafer has fifteen contacts. The large number of
contacts is used, to carry the peak level of power that a hard
drive can draw. The 15 contacts were basically intended to be
five groups of three. The groups would be +12, GND, +5, GND, +3.3V.
The three contacts per group, help carry the number of amperes
needed by the drive. The standards group did fool around with one
of the pins, and tried to define it for a logic function, but
that doesn't seem to be in use that I can see. (In theory,
it might have supported connection to a LED, so drive activity
could be viewed by the user.)
The old Molex plug has four connections, +12V, GND, GND, +5V.
The SATA has +12V, GND, +5V, GND, +3.3V. When you buy adapter
cables, that go from Molex to SATA_Power, there is no 3.3V
available on the Molex, so the SATA_Power ends up with no
3.3V on it either. Some day, drives which use 3.3V may come
along, in which case that style of adapter cable won't work.
The most likely reason for the 3.3V to get used, might be
when flash drives become more popular. But just as easily,
they could put switching power conversion inside the drive.
It remains to be seen whether the "missing 3.3V" on those
adapter cables, will ever become an issue. (I'm using
an adapter cable right now, so I hope not.)
When SATA is provided by a modern ATX power supply, there
is no problem connecting all five wires to it.
Paul
)