pc power supply

[kujawski]

I have a 400 watt power supply in a pc, how many hdisks can i safely use,
i have 1 hd on the primary plus a cd,
and an pci card which can support another 4,
would that be too many,

thanks

[ChuckFickens]

And how many CD drives do you have, what CPU, what Graphics card, how many case fans, how many USB devices?

They all use power (some graphics cards use well over 300W on their own) so it's not possible to answer from the information given.