On Tue, 31 Aug 2010 01:26:23 +0100, "Arfa Daily"
wrote:
Have you any idea just how much processing power it takes to run a
user-interactive story in real time, and then to 3D render the graphics in
real time ?
Well, no. I'm not a power user. What little rendering I do is with
bacon fat.
Do you think that they rate the 12v PSU for 23.5 amps in one
version, and 32 amps in the other, for fun ? Those are not real questions,
because I know full well when you stop and think about it, you know the
answers, Jeff.
Actually, I don't know. I don't have any customers with such machines
and have had zero experience with high power graphic workstations
(other than early 1980's Applicon CAD stations) or game machines. I
have worked on various network servers, which do burn such power
levels. I have looked at a 3D MRI image processor, which had some
manner of dedicated processor inside, but it certainly wasn't belching
400 watts of heat (my estimate by the amount of fan noise).
I've just looked at the rating plate on the bottom of one of the cases, and
it is 240v (nominal UK line voltage) at 1.8 amps. I make that a maximum
input power of around 430 watts. It's a switching PSU, so I reckon that we
can rate that as being at the very worst 80% efficient, so that's still 345
watts potentially going somewhere. I'm prepared to go with 45 watts into
ancillary circuitry on the board, which still leaves around 300 watts going
somewhere. Perhaps I'm being naive, but my best guess is that it's
disappearing into the two bloody great BGAs which the manufacturers are
trying their utmost to heatsink. If you try to run one of these machines
with the heatsinking not in place, it goes into thermal protect in about 5
seconds - and all it's doing then is booting. The heatplates on the BGAs are
at this point hot enough to take your fingerprints off ...
Nope, I'm pretty sure that these two puppies are good for 150 watts apiece,
when the machine is doing some real work.
Ok, I stand corrected. I've been assuming that the CPU's are doing
most of the power dissipation. I didn't think of a dedicated graphics
processor or whatever the BGA chips are doing. Do you have a gun
style IR thermometer? I use that to determine if anything is running
hot. I use a black (non-reflective) cardboard tube attached to the
lens to prevent it from picking up adjacent components. Incidentally,
I have yet to find one where the laser dot actually points to where
the device is measuring when in close proximity. You can also get a
rough idea of how much effort is going into cooling. If the BGA's
burn more power than the CPU's, then they're going to need more
massive heat sinks and better air cooling. At 400 watts, I would
think they would have gone to heat pipes and external radiators or
maybe liquid cooling.
Incidentally, I repaired a P4 motherboard yesterday which used Artic
Silver. My guess is that there was about 5 times as much Artic Silver
smeared over the CPU (and down the sides where it does nothing) as
necessary. The stuff down the sides was still fluid, so at $10 for
3.5 grams, I saved the excess.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558