[lewzer]

And your box is always @ full Load?

mmm no. But I don't understand your point. My htpc probably consumes 3-4W at Idle, I should be close to the numbers Dougie has posted above. PSU is a wall wart, SSD turns itself off during sleep... My objective with this build was the lowest power "confortable" desktop environnement + XBMC on top for cheap.

Then i don't know why you argument with FullLoad Watts?! Haswell and Baytrail should be similar in Idle.

Propably? Don't you know it? Which Components your HTPC consist of?

Baytrail:
ASRock Q1900B-ITX - 60eur http://geizhals.de/asrock-q1900b-itx-90-...89506.html
PicoPSU - 60 eur http://geizhals.de/mini-box-picopsu-90-9...63445.html

HSW:
http://geizhals.de/?cmp=995560&cmp=1044348&cmp=425982 - 110 eur

I don't see the big Benefit in Baytrail, Performance wise the HSW should be faster:
http://www.cpubenchmark.net/compare.php?...cmp[]=2129
And the HSW GPU can make Yadif + Lanczos3, the IVB GPU in Baytrail not.
So why should i buy Baytrail?

It is not worth getting the single PicoPSU in your case. I've ordered Q1900-ITX and a case for it few days ago.
The Q1900-ITX (NOT B!) cost me 67EUR and a nice case - 58EUR, so a total of 125 eur compared to 110eur vs haswell. However, for the extra 15 EUT you do get an actual case.
The shop that I bought from -
Q1900-ITX - http://www.reichelt.de/ASR-Q1900-ITX/3/i...=q1900-itx - 67.12 EUR
MINI ITX-E-I5 - http://www.reichelt.de/MINI-ITX-E-I5/3/i...I+ITX-E-I5 - 58.72 EUR

Total - 125.84 EUR + 6.95 EUR shipping

VS yours suggested HSW

Intel Celeron G1820 - http://www.reichelt.de/CELERON-G1820/3/i...eron+G1820 - 33.51 EUR
ASUS H81T - They are not selling this motherboard so lets take a price from your suggested link - http://geizhals.de/asus-h81t-90mb0hu0-m0...44348.html - 67.90 EUR
Cheapest 90W PSU I could find - http://www.reichelt.de/FANTEC-NBU90W/3/i...iversa+90W - 30.99 EUR

Total - 132.4 EUR + 6.95 EUR shipping + atleast 12eur shipping for the MOBO.

Anyway, my point is, the prices in 'geizhals' are without shipping and it is sorted by the cheapest price. The cheapest prices usually have insane shipping and extra costs (for example - you have to pay like 10 EUR extra of 'processing fee' and then a 20+EUR shipping). I've tried to compare prices from the 'reichelt' shop since they do offer quite nice prices and cheap shipping without any extra hidden fees.
To my calculation the HSW system is atleast 10% more expensive compared to mine (and you do not get a case). Is it worth the extra 10%++? Probably yes. But then again, they are quite different beasts so to say. One is fanless, other one is not. One is designed to be as low TDP as possible, other one is not.

The performance wise j1900 on CPU benchmarks shows a score of 2052 while the G1820 Celeron - 2702. So yes, both GPU and CPU score wise the G1820 is better
But when it comes to MAX TDP - J1900 - 10W versus G1820 - 53W. More than 5 times higher.

To sum it up - I think you did a bad comparison with the prices. You are comparing a motherboard that has a built in DC jack versus one that does not and requires a case or pico PSU. To 'even the odds' more I'd compare yours suggested build with Q1900DC-ITX which will be coming out in Japan very soon (within few days) and should have a retail price of about 80EUR. Add a 60W PSU to that and you will get a total of ~100 EUR.