On Wed, 14 Apr 2004 20:23:48 GMT, (John Lewis)
wrote:

Nvidia 6800 Ultra: 110 watts maximum

Power Supply:-

480 watts minimum !!!


For those wondering about the above figures, Nvidia have chosen
to specify Power Supply watts, not the exact current required for
the 6800U from the +3.3. +5 and 12 rails. I have no idea why they
have chosen to do it this way, except that most non-technical
folk have no idea how to relate watts to current from the
point-of-view of matching a power-supply to the power-demands
of a card. Specifying 480watts is likely to give ample headroom
for worst-case variation in the currents available from that class of
power-supply. I suspect that the amperage demand in the 6800
Ultra on the 12volt supply is the culprit. On-board
switching-regulators are most efficient with the highest-value input
volts. Most, if not all, 480 watt power supplies can deliver at
least 18 amps on +12V (216 watts max) which should be just
about enough to drive the 6800 Ultra, the CPU, plus all disk
drives and other peripherals also requiring +12V.

Anyway, the difference in price between a 350 watt and
480 watt power-supply is tiny and most enthusiasts have
already upgrade their power-supplies to something in the
suggested range.

I would suggest that for any wondering whether their
existing power-supply is sufficient that they check the
Power Supply label. If AT LEAST 18 amps at 12 volts,
AND at least 350 watts they should probably give the
6800 Ultra a whirl before rushing out to buy a new supply.
Anything less than 18 amps from 12 volts -- budget for a
new power-supply, especially if you are running a
top-end CPU.

John Lewis




Preferably 4 "disk-drive" cables available from power-supply.
Two must be available EXCLUSIVELY for the 6800 Ultra.
( minor exception --- auxiliary fans are allowed to co-use
these cable feeds )

Power-supplies with only 3 cables will need some $2 splitters
on the third cable for the various disk drives --- not a real
problem, since their power consumption is very low.