I have an Antec Minuet II case with comes with an Antec Smartpower 2.0 450W PSU (modified, power connector at the other side and one 120mm fan instead of 2x 80mm). Exactly the same unit otherwise.
The first unit was heating up even when the pc was not running, I measured temperature overnight and it rised to about 55Â°C. on top of the PSU. I asked a new PSU, installed it but it didn't change, again a hot PSU while the PC wasn't even running. After 6 months of plugging out and in the power cable I again asked for a new one, hoping they fixed this issue. Before sending it back to Antec I closely watched between the vent holes of the PSU and I saw clearly a faulty (swollen at the top) capacitor (take a look at www.badcaps.net
for more information about the bad capacitors plague).
When waiting on a replacement PSU from Antec I've temporary used an Aopen 300W PSU and this one didn't heat up overnight and it was even more quiet too!. The new PSU from Antec arrived, I installed it and it lasted... about 2 hours... then suddenly black screen and my PC wouldn't turn on again. I replaced it with the Aopen, no problem. Again replaced with the antec, no power. So this one has terminated itself, nice... Again I contacted antec, they asked me to cut the wires from the PSU and take a picture of it so they could send me asap a new one and I didn't have to send the faulty one back.
I received the new PSU, installed it and again... overnight it is heating up to 55Â°C. I am tired of it and don't trust the smartpower PSU. I replaced it with the Aopen 300W (which can deliver more current on the combined 3.3V and 5V rails: 200W instead of 150W) and since I use an AthlonXP 2500+ (runs at a very safe XP2900+ speed at default voltage on a motherboard with no bad capacitors) which has no use for the extra 12V P4 connector.
I've rerouted the power cable in the case so it can connect to the aopen PSU internally, the fan of the PSU is blowing outward the side of the case so this is good, the only drawback is that the PSU takes 'hot' air from within the case instead of the 'fresh' air from beneath the case...
I'm a bit disappointed that Antec doesn't do something about this powersupply, I'm sure I'm not alone with problems (a friend also had a smartpower 450w in a sonata II case, suddenly his PSU made a strange noise and the pc didn't boot, he replaced it with an antec neotec and is happy with it now).
Since my Minuet II case has a customized Smartpower PSU it's difficult to use a regular PSU (cooling issues/power cable difficulties) but I'm happy with the quiet Aopen PSU (wich does weight a lot more than the Antec by the way). I don't recommend the Smartpower series PSU, stay away of them and if you have one, measure temperature overnight and take a good look inside the PSU to check if you have bad capacitors.