In order to get the most power efficient system is important that the idle loads falls around 20% of minimum load of the psu.
This because 80 plus psu certification ask manufacturers guarantee a minimum efficiency of 80% or more that load...but nothing is asked on 5%-10% load
That is true of most run-of-the-mill PSUs, but he said the magic word: Seasonic.
While I don't have reviews of
that particular PSU (because hardly anyone does rigorous performance testing of low-end models), most of Seasonic's PSUs vastly overperform the specs at low-loads. For example, their
current Platinum Series 860w model does ~80% at 5% load, and the older Gold series were
quite good as well. Besides... How much difference in the real world is the difference between a 300w @ 80% and a 400w at 75%? Maybe $4 over a year? Of course, if you're doing it for the planet, that's fine, but you'd probably be better served saving your pennies for a windmill or something.
In any case, if you aren't going with a discreet GPU, you don't need much of a PSU at all. I'd still go for a Seasonic though, as I've found them to be VASTLY longer-lived, quieter, and more stable than any other manufacturer I've tried. PSU stability problems are COMMON, and people never know it because they never check their systems under load.
Sometimes, you get what you pay for. That's not the main reason I commented though...
I think that the perfect htpc cpu will come in october...but this another story
This is why I really commented. This type of sentiment is very common, and it
mildly annoys me... The perfect HTPC CPU
for your needs, perhaps. It all depends on what you want to do with it. Many people, granted, look at a HTPC like you are, and that is fine if that's what you're going for.
I, however, have
zero interest in an underpowered but small HTPC. I want the HTPC in my house to be among the most powerful computers in my house, not the least. It needs to be in a full-sized ATX case (though doesn't necessarily need a full-sized ATX board). Why? Well, a few reasons:
1. It is the machine I use more often than any other in my free time. I want a very high-performance machine that performs without hesitation. SSDs are an absolute requirement for me, for example. It needs to
leap at the touch of a button.
2. I play games on my HTPC. I need to be able to fit a good sized GPU in the box, and power it. It doesn't need to be a $500 behemoth GPU anymore because it is only driving 1080p. But even my current AMD 6870 is starting to get a little slow at 1080p in some current games. I have to turn down settings now and drop back on AA. You mentioned the GT430, which is the
worst possible card for me that I can think of, for example (way overpriced and underpowered).
3. It does a fair bit of on-the-fly video transcoding and compression (ripping BluRay and whatnot), and Quicksync is a piece of crap, so I need real CPU power in that case.
So, not to come off like a jerk at all... I know what you meant. But not everyone thinks a HTPC should fit in a MiniITX box and run the slowest/lowest-power CPU you can get that still barely performs basic media playback tasks. Opinions, and needs, on this can vary substantially.
I wouldn't even
think about using anything less than a quad-core i5 on my most-used system. For you, one of the coming Ivy i3s might be completely sufficient (even overkill) for your needs. One thing is often not like the other.