Intel boards seem pretty good for power efficiency, and DH67CF is one of the few mini-ITX with DisplayPort. However, does it have a BIOS option to undervolt CPUs?

No, it doesn't seem to.

I don't think you can on the Intel H67, at least my DH61DL you cant, even the memory voltage although you can change it in the BIOS, seems it doesn't kick in, the voltages still seem 1.5V under windows. But the Intel mobo should idle extremely low at stock settings, i manage to reach 14W on my Intel H61 + 2100T (no keyboard, mouse or monitor), 15W idle is common in most reviews i seen, so i would go with that board even if you cant undervolt, i doubt you will get much lower than that. If you want to reach as low as you can go for picoPSU style PSU and as low fans as you can, my fans consume between 1 to 2W each. Now if its more for lower heat or trying to go passive, out of luck with intel, probably give up on display port and go with another brand.

Thanks, how did you find out? do you have one or were you able to find a manual listing the BIOS options?

Not a total deal breaker with this board, just have to be sure and choose a lower TDP if I opt for a lower power PSU.



Thanks to you also. I want to stay relatively power efficient for the build and I'm trying to figure out the picoPSU + brick combination or some alternative. A couple of options around 90W are reasonably priced compared against the 120W & 150W versions, but I'm not too sure I'd want a 95W TDP CPU on a 90W PSU...

Well if you are aiming at efficiency, i would probably go with the combo from JonnyGuru PicoPSU roundup, pico-PSU-120WI-25V + FSP120-AAB (crosscheck is the right one).

Why?

Most reviews show 3-5W idle for the CPU. Focus on other areas. Low power disk drive. Power supply that is efficient at low draws (like the PicoPSU). Even fans may pull 2-3W each.

To get lower power consumption at load.

I have one in my general-purpose/gaming rig. There are tweaking options for memory and graphics but seemingly not for the CPU.

SS-400ET
2500K
DH61WW
4GB DDR3 1333Mhz
500GB WDC 6Gbps

PC (CPU Power package)
IDLE: 23 W (5 W)
7ZIP: 80 W (45 W) 13500MIPS
CB11.5: 90 W (55 W) 4.9 pts

The isolated CPU Package power data includes: GT Cores, IA Cores, L3 and NB. as shown by HWinfo32:Sensors.

Specific CPU VIDS are tied to each CPU ratio :
Ratio SVID
16x 0.9907
17x 1.0057
18x 1.0208
19x 1.0358
20x 1.0458
21x 1.0608
22x 1.0758
23x 1.0908
24x 1.1058
25x 1.1208
26x 1.1359
27x 1.1509
28x 1.1659
29x 1.1809
30x 1.1959
31x 1.2109
32x 1.2260
33x 1.2410
34x 1.2660

Seems to me the only way to get it to 1.1 Volt is to choose 24x ratio in bios.
Or something"T" and something"S" CPU with 35/45W TDP with naturally Low Ratio and VID, but limited in so many ways.
No VT-d in 2500K though.

during the test 2500K was at maximum 34x 1.2660V and 16x 0.800V in idle.
DDR3 memory was at 1.5V. minimum stable was 1.35V. 1.30V had linpack error, 1.25V didn't boot. By default the motherboard supplied 1.57V.
Maximum CPU power usage reached was 55 Watts while rendering.

3.5" Drive was used, so the power usage is up by 10 watts., results with 2.5" or SSD showld be 10 watts lower.
Considering the PSU efficiency of 400ET is below 60%, 23 Watts IDLE AC power consumption measured at the wall is impressive isn't it?

I'm upgrading my SageTV server which idles at ~85W with a Q6600, Asus mATX board, 2x2GB RAM, Corsair 450W PSU. Looking at several alternatives, will also create an additional file server too. Inspiration from Matt Garmin, Green Frank, others here, and a LOT of reading on German website Hardwareluxx, some real low power nuts.

Common components, wired PS/2 keyboard, USB mouse, onboard graphics ==>VGA==> LCD monitor

1) AMD Sempron 140 unlocked to dual core, Asus M4A785-M, 2x1GB RAM, Intel Pro PCI-e x1 NIC (uses 2W), 3.5" WD 640AAKS OS drive, 3 Samsung 2TB drives, Seasonic 300W Bronze PSU
Using heavily modded Kstat10 settings, shut off unused devices in BIOS. Same readings if single or dual core.....scratches head. Asus EPU-4 software no diff.
Win7 OS power save mode etc.

p0 @2700MHz 1.0875V = 84W with Prim95 running
p1 @1900MHz 0.9250V = 74W " " "
p2 @1500MHz 0.8375V = 69W " " "
p3 @ 800MHz 0.7125V = 64W " " "

Idle at 41W
Max CPU 84W (running Prim95 large FFT)

2) Intel DH61WW, i3-2100, 1x4GB RAM, 3.5" WD 640AAKS drive, Seasonic 300W Bronze, updated BIOS (adds tabs, not many useful options though), shut off parallel/serial ports, sound, etc. No other tweaking done.
Win7 OS power save mode, etc.

Idle 26W
Max CPU 51W (running Prim95 large FFT)

Idle Ubuntu 11.04 "Natty" 23W
Adding in the 3 additional Samsung 2TB drives idle is 39W, with drives "spun down" idle is 28W in Ubuntu desktop. Unity, yuck.

Tested using KillaWatt. Sylvania 75W light bulb measures 73W, generic 40W was 39W, and generic 100W was 91W. I am not sure about these cheapo bulbs, trust the meter more.