The specified Dell power supply is rated for 12 Amperes supply current (from the AC mains) for 110 Volt AC mains, and 6 Amperes supply current for 220 Volt AC mains.
This translates roughly to 1320 Watts of maximum power drawn from the mains (typically at start-up).
Efficiency rating at maximum load is stated as 87%, hence peak output power is no more than 0.87 x 1320 = 1148 Watts
instantaneous / start-up power.
All of this has little or nothing to do with the 825 Watts continuous power rating of the power supply, as we will see.
How does the 825 Watt value fit in with the current ratings for the various output lines of the SMPS? Actually, it never does.
The data sheet states that:
- Each +12 Volt line supports 18 Amperes (7 lines) = 1512 Watts!
- The +5 Volt line supports 4 Amperes = 20 Watts
- The -12 Volt line supports 0.5 Amperes = 6 Watts
While it is tempting to simply add those values up to get an output wattage, that isn't how a PC power supply is expected to work. In reality, individual supply lines will have differing loads at various instants, with the transients being fulfilled by reservoir capacitors at these outputs. So long as each individual output is loaded within its specification, and the combination of actual loads does not exceed 825 Watts, everything runs smoothly.
Beyond that point, regardless of which specific outputs are most heavily loaded, the on board processor of the SMPS will throw an overload alert, and attempt to gracefully shut down the system.
For less sophisticated PC SMPS units, the "graceful shutdown" is a myth, but with server grade power supplies, there is typically control logic in there to notify the operating system of a power supply problem, and then downgrade or cut off specified outputs (look for the technical reference) until the load returns to the safe operating area. The server OS is in the meanwhile expected to raise appropriate alert flags, save machine state to disk, and shut down until manual intervention.
There's nothing wrong with a power supply that has 10-15 connections; that's actually fairly typical for supplies in this class. You just need to understand what they're for.
For the power input, there will be connections for line, neutral and ground. There might be a separate "frame ground".
For the output, there will be at least one pair of output terminals (maybe more), possibly a pair of "remote sense" terminals (which help compensate for voltage drops in the wiring), and possibly terminals for remote adjustment or load-sharing.
The datasheet for the power supply should show how to hook it up for various application scenarios.
Best Answer
You need to rethink your calculations.
Let's assume that the amplifier you're using has negligible losses. Then the very greatest power you can provide to the speaker is (12 volts x 12 volts / 8 ohms), or 18 watts. Music, though, is essentially sinusoidal, so the maximum sustained AC power, technically called RMS power, is 0.707 times the peak power. This means that your amplifier can only produce 12 watts. Note that the data sheet you linked to suggests a 22 volt power supply. Checking this against the previous calculation gives (22 x 22 / 8) x .707, or 43 watts RMS. And using the absolute maximum of 24 volts gives 51 watts. Close enough.
So the peak current will be 12 / 8, or 1.5 amps per channel, for a total current of 3 amps, and a total power supply requirement of 36 watts.
So, to answer your question, the unit does not pose a fire hazard. It doesn't provide nearly as much power as you thought it would, but that's a different question.