Power requirement for H97-D3H motherboard

I expect to purchase this motherboard, but am unsure about whether I can
use an Enermax 450 Watt power supply I happen to have in hand. I don't
plan to overclock the board or use it for gaming. The cards are likely
to be a modest audio and wifi card, and there will be one or two SATA
hard disks. The audio card is because the onboard audio chip is reported
to be flakey with the Linux OS.

Haines Brown

Haines Brown wrote:
I expect to purchase this motherboard, but am unsure about whether I can
use an Enermax 450 Watt power supply I happen to have in hand. I don't
plan to overclock the board or use it for gaming. The cards are likely
to be a modest audio and wifi card, and there will be one or two SATA
hard disks. The audio card is because the onboard audio chip is reported
to be flakey with the Linux OS.

Haines Brown


Some of the parts of the computer draw more
power than others, and are key elements in
working out the power draw.

Video card - look it up. Xbitlabs has measured older cards, but has stopped
doing power when reviewing cards. GPUReview.com stopped adding
information content to their site a year ago. A manufacturer,
Club-3D, copies available info to the spec sheet for the card.
For example, my new HD6450 (a 3 year old chip), is on the order
of 16 watts. Some other cards might be 250W (max).

CPU - you can use the TDP as a gross estimate. For example, I bought a 65W TDP
processor maybe 4 years ago, and flat out, it drew 36W. I bought another
one with smaller geometry, and it drew 43W. I just bought a 130W processor,
and as measured at the yellow wires on ATX12V, it is 12V*13A = 156W. TDP
numbers tend to cover "classes" of processors, and the high end of a range
will be close to the TDP value. The anomaly in my results, is possibly
caused by the BIOS option which amounts to overclocking (effectively turbo
applied to all cores, instead of following the turbo table)

Motherboard - I allocate 50W for this, based on say 2W per DIMM times four
DIMMs, 25W chipset for some of the more extravagant ones, and
so 50W should well cover it. Maybe this covers a NIC card (1 or 2
watts) that I added, or an IDE card (another watt or two). The
motherboard I just pulled out of its case, would be under 20W,
a real economizer (VIA chipset).

Disk - 12W (spec - varies a bit)
Optical - 17W (measured with media spinning, drops to maybe 5W idle)

USB bus - 5V @ 2A est = 10W

16 + 156 + 50 + 12 + 17 + 10 = 261W

Your 450W would be enough for me. I would have to go through and
work out amperes on each output, just to be sure, so there's more
to it than that. But as a first cut, your supply would not
be out of line for my power loads. Most of my power draw
would be from 12V.

*******

There are web sites which will do the arithmetic for you. The Asus
site, rounds to the nearest 50W, which causes anomalies if you're
attempting to ferret out what Asus uses for power for each component.
Another site, at one time they were so inaccurate, the number
was 2X the proper value. They've since improved their results
a lot, so they might be 10% on the high side. I remember seeing
one site claim DIMMs were 25W each, which for modern memory types
is absurd. DIMM power is defined by cycle type, with refresh cycles
taking little power, read/write taking a lot more, and the data
sheet for the DIMM should be using the "industry average mix" for
cycle types, to rate the power. And 2W is where an average DIMM
might be now. (Look up some Kingston DIMMs, as they have
datasheets with a power number. That's where I get my "averages"
from, is Kingston.) So when a site insisted on using 25W, and one
poster entered 12 DIMMs as his memory quantity, the power numbers
were quite far off.

One reason for overestimating, is at least one of those
sites used to sell power supplies :-) And I think you
can see the conflict of interest possibilities there. That
site no longer offers the power calculator.

Anyway, that's a very brief overview, to get you in
the right ball park. The CPU and video card draw from +12V,
while the motherboard 50W number is from 5V and 3.3V rails.
You can use those data points, to work out whether you're
exceeding the 12V rating or not.

As an example, my supply is rated 12V @ 34 amps max, my processor
is using 13A, my video card 1 or 2 amps, my fans might use 1 amp
total, so I'm on the low side of 17 amps, just using those
major loads as a check. Plenty of room. My CPU only uses 13A when
running flat out. It actually drops down to between 1 and 2 amps
just sitting in the desktop and not doing anything. But when
buying a power supply, for planning purposes, I have to assume "13A
forever", as a worst case.

If you're running a server with 25 disks in it, the spin up current
of 3 amperes per disk, is significant. That's enough to tip over
a lot of supplies. You say you're not using a lot of disks, so I
have not worked any examples of this issue. When a lot of disks
are involved, you do two power calculations. One power calc for
T=0 conditions (CPU light load, disks 3A each), and a running system
calc (CPU heavy load, disks at 1A each on 12V rail). Back in SCSI
disk days, they used "staggered spin" to smooth out the T=0
power, and I gather some sort of thing like that is still available
in the server room.

Paul

Paul writes:

Haines Brown wrote:
I expect to purchase this motherboard, but am unsure about whether I can
use an Enermax 450 Watt power supply I happen to have in hand. I don't
plan to overclock the board or use it for gaming. The cards are likely
to be a modest audio and wifi card, and there will be one or two SATA
hard disks. The audio card is because the onboard audio chip is reported
to be flakey with the Linux OS.

Thank you for your very interesting and informative reply. I did the
best I could to estimate power requirements and came up with 350W. I
suppose 450 Watt power supply could handle it, although it would leave
little breathing room. I suppose one should have a power supply
significantly larger, but since I have a new 450W supply in hand, I'd
like to try using it.

What happens when demand is a bit too much for a power supply? Would
rail voltages begin to drop, or will the supply shut itself down before
that occurs?

Haines

"Haines Brown" wrote in message
...
Paul writes:

Haines Brown wrote:
I expect to purchase this motherboard, but am unsure about whether I can
use an Enermax 450 Watt power supply I happen to have in hand. I don't
plan to overclock the board or use it for gaming. The cards are likely
to be a modest audio and wifi card, and there will be one or two SATA
hard disks. The audio card is because the onboard audio chip is reported
to be flakey with the Linux OS.

Thank you for your very interesting and informative reply. I did the
best I could to estimate power requirements and came up with 350W. I
suppose 450 Watt power supply could handle it, although it would leave
little breathing room. I suppose one should have a power supply
significantly larger, but since I have a new 450W supply in hand, I'd
like to try using it.

Should be ample - remember not everything is going to run at max power at
the same time.

Efficiency should be good too.


What happens when demand is a bit too much for a power supply? Would
rail voltages begin to drop, or will the supply shut itself down before
that occurs?

It would tend to overheat first and then stop on thermal cut out.


Haines

Haines Brown wrote:
Paul writes:

Haines Brown wrote:
I expect to purchase this motherboard, but am unsure about whether I can
use an Enermax 450 Watt power supply I happen to have in hand. I don't
plan to overclock the board or use it for gaming. The cards are likely
to be a modest audio and wifi card, and there will be one or two SATA
hard disks. The audio card is because the onboard audio chip is reported
to be flakey with the Linux OS.

Thank you for your very interesting and informative reply. I did the
best I could to estimate power requirements and came up with 350W. I
suppose 450 Watt power supply could handle it, although it would leave
little breathing room. I suppose one should have a power supply
significantly larger, but since I have a new 450W supply in hand, I'd
like to try using it.

What happens when demand is a bit too much for a power supply? Would
rail voltages begin to drop, or will the supply shut itself down before
that occurs?

Haines

You might see some droop if it's on the edge.

If you don't have a monster video card, I doubt it's 350W.

Were you using this one ?

http://extreme.outervision.com/PSUEngine

Paul

Paul writes:

Haines Brown wrote:
Paul writes:

Haines Brown wrote:
Thank you for your very interesting and informative reply. I did the
best I could to estimate power requirements and came up with 350W.

If you don't have a monster video card, I doubt it's 350W.

Paul, the old card I'm likely to use is a MSI NX8500GT. Hardly a monster
card, although the specs say it is 144-163 watts.

Haines

Haines Brown wrote:
Paul writes:

Haines Brown wrote:
Paul writes:

Haines Brown wrote:
Thank you for your very interesting and informative reply. I did the
best I could to estimate power requirements and came up with 350W.

If you don't have a monster video card, I doubt it's 350W.

Paul, the old card I'm likely to use is a MSI NX8500GT. Hardly a monster
card, although the specs say it is 144-163 watts.

Haines

It's 40W.

http://www.gpureview.com/GeForce-850...-card-514.html

Xbitlabs didn't measure that one, and the closest they got was
8600GTS at 47W. And when a card doesn't have a PCI Express connector
on the end, that generally caps the power at 12V @ 4.3A or 52W. The
video card designers don't try to take the PCI Express slot to the
max, and that's the highest known consumption (measured).

So the 40W number is a reasonable one. If there is no 2x3 connector
on the end of the card, it's a lower power one.

Paul

Thanks for the correction Paul.

I wonder if I might slip in another petty question here regarding this
motherboard rather than start a new thread: can its Secure Boot be
disabled?

Haines

Haines Brown wrote:
Thanks for the correction Paul.

I wonder if I might slip in another petty question here regarding this
motherboard rather than start a new thread: can its Secure Boot be
disabled?

Haines

The features of Secure Boot, are purely up to the company
making the hardware.

On a Windows RT box, Microsoft compliance would require Secure
Boot to always be enabled. And the trust key used, would
only allow the Windows OS to run. No key for Linux or Android.

On an x86 desktop, you would have more options. Secure Boot
is turned off in UEFI BIOS on my new motherboard. My
motherboard also claims to have key management, and so
if I wanted to use Secure Boot, and add another OS
to the list, there is supposed to be some way to do that.
Motherboards like mine are supposed to have a Windows key
and a Linux key, but I don't care enough to check for that.

To me, Secure Boot is just an exclusion mechanism, and
it is mainly (ab)used at the moment for mobile devices.
The ones where they want to build "Walled Gardens".

Paul