Question about the P/S test in MYOD post

Ok, when the disk began spooling, the fans increased RPM's slightly, then dropped off a bit, and THEN increased to twice the speed of their first spool. Does this make sense? I'm upgrading my factory, (Dell), 250W P/S to an Antec SmartPower 350W but I also plan to add a Radeon 9700Pro and maybe upgrade to an Audigy 1 soundcard from an SB Live 5.1.
Would the Antec 350W be adequate or should I purchase a 400W? Currently on 250W's I run:
P4 2.4G (533mhz FSB no hyper-thread)
512Mb dual channel @ 333mhz
Dell MOBO
GeForce4 MX 440 (Radeon 9700Pro eventually)
Sb Live 5.1 (maybe Audigy eventually)
1 7200Rpm Cd-Rom
1 Cd-Rw (rarely used)
56K modem
USB joystick

Any help is always appreciated! Thanks!

HP uses standard boards and standard power supplies. Boards and power supplies have been on the market a long time that allow the fan to be connected to the motherboard, or the RPM sensor. Most HP's I've worked on didn't even have that feature, it must be a recent thing.

Dell recently changed to ATX power supplies and proprietary boards (around 2 years ago, depending on model). I don't know which models use ATX and which use Dell power.

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