Yet another bulging-capacitors replacement

Thanks for the insights Jeff. All interesting stuff. These are
dedicated games machines, not based on a PC in any way. The power
supply is specced to deliver 12v at 23 amps, yes, that's twenty three
amps ...

Almost all of this is potentially going into these two processors, so
not far off 300 watts between them. No mean task shifting the heat off
them !

Arfa



what processors(microprocessors?) run at 12V?
ISTR that today's uPs run mostly on 3.3V

Most other digital logic runs at 5V,I believe.

I think you wil find that most of your power is going into the video
drive
(or LCD backlight) circuitry.

--
Jim Yanik


Er no. There are no backlights. Or display processor. These are X-Box /
Playstation type boxes. Apart from some support circuitry in IC form -
which admittedly does gobble enough power to make it run hot enough that a
degree of heatsinking to the pcb shielding via thermal pads is required -
everything goes on in a pair of very large BGA processors, one of which is
the data processing engine, and the other of which is the graphics
processing engine. It is they which make use of the 12v, and they which
gobble the amps from it ...

The power supply does have other outputs, but these are all at very low
current availabilities, so will be for support logic and maybe some core
supplies for the two processors. Trust me when I say that the two big
chips is where all the power is going, and generating heat that needs
shifting :-)

Arfa

Thanks for the insights Jeff. All interesting stuff. These are
dedicated games machines, not based on a PC in any way. The power
supply is specced to deliver 12v at 23 amps, yes, that's twenty
three amps ...

Almost all of this is potentially going into these two processors,
so not far off 300 watts between them. No mean task shifting the
heat off them !

Arfa



what processors(microprocessors?) run at 12V?
ISTR that today's uPs run mostly on 3.3V

Most other digital logic runs at 5V,I believe.

I think you wil find that most of your power is going into the video
drive (or LCD backlight) circuitry.

--
Jim Yanik


Er no. There are no backlights. Or display processor. These are X-Box
/ Playstation type boxes. Apart from some support circuitry in IC form
- which admittedly does gobble enough power to make it run hot enough
that a degree of heatsinking to the pcb shielding via thermal pads is
required - everything goes on in a pair of very large BGA processors,
one of which is the data processing engine, and the other of which is
the graphics processing engine. It is they which make use of the 12v,
and they which gobble the amps from it ...

The power supply does have other outputs, but these are all at very
low current availabilities, so will be for support logic and maybe
some core supplies for the two processors. Trust me when I say that
the two big chips is where all the power is going, and generating heat
that needs shifting
:-)

Arfa

Odd that BGA processors are using 12V instead of logic level voltages.

I'm surprised they don't use some sort of liquid or heat-pipe plumbing to
remove all that heat. Wasn't it the CRAYs that used liquid Freon to flood
the processor cabinet to dissipate al the heat built up?

"Arfa Daily" <arfa.daily_at_ntlworld.com> wrote in
news:dgZdo.79946$Pa3.38201_at_hurricane:



"Jeff Liebermann" <jeffl_at_cruzio.com> wrote in message
news:jh3e761hp6mg3b0sb1h6stsdsq19g2mk0m_at_4ax.com...
On Fri, 27 Aug 2010 01:27:14 +0100, "Arfa Daily"
arfa.daily_at_ntlworld.com> wrote:

Anyone
else got any constructive comments on the subject of thermal
interfacing of
coolers to high power chips ?

In a past life, I used to design HF SSB marine radios. The typical
transmitter was Class AB 150 watts with about 30% efficiency. That's
two devices, dissipating about 125 watts each, over an area of about
70 sq-cm. Oh yes, no fan allowed.

This is quite a bit more dissipation than the average desktop, causing
some things to be more critical. In the process of getting it to
work, I learned a few things.

1. The less silicon grease used, the better. The idea behind silicon
grease is to fill in the gaps, scratches, and gouges in the power
transistor base and aluminum heat sink. Cross sectional
microphotographs show metal to metal contact on the peaks, but huge
gaps, filled with silicon grease, in between. Under ideal
circumstances, maximum metal to metal contact, with minimum gaps is
the target practice.

2. All heat sinks and transistor bases are NOT flat. I made a
dramatic improvement to the measured thermal resistance by polishing
flat the base of the xsistor and the face of the heat sink. That
meant removing the gold from the copper base, but that's what was
necessary. I used a Moire pattern to measure flatness. A mirror
finish was best, but difficult to achieve. To prevent corrosion, I
plated the exposed copper with electroless tin or silver. For the
aluminum heat sink, I just used abrasive polish and a glass polishing
plate to obtain a mirror finish and flat surface.

3. Compression pressure is important. None of the standard spring
clip CPU heat sink holders come even close to optimum. Compression
adjusts for the bends, and also provides some level of galling to
provide metal to metal contact. If done correctly, adding silicon
grease actually increases the thermal resistance. However, this is
difficult to do with a CPU that has components on the bottom side,
thus preventing compression. Applying pressure only on the top center
of the CPU, will cause the substrate to bend, and eventually break. I
have some ideas, but nothing that can be retrofitted to an existing
motherboard and CPU socket. This is close, but not optimum:
http://www.frostytech.com/articleview.cfm?articleID=2273> Note the
comments on base finish and flatness.

So, if you want the best head sinking, polish flat the CPU top
(removing all the laser scribbled markings, polish the heat sink face,
use very very very very little silicon grease, and compress the
sandwich until it nearly breaks the CPU.

--
Jeff Liebermann jeffl_at_cruzio.com


Thanks for the insights Jeff. All interesting stuff. These are
dedicated games machines, not based on a PC in any way. The power
supply is specced to deliver 12v at 23 amps, yes, that's twenty three
amps ...

Almost all of this is potentially going into these two processors, so
not far off 300 watts between them. No mean task shifting the heat off
them !

Arfa



what processors(microprocessors?) run at 12V? ISTR that today's uPs run
mostly on 3.3V

Most other digital logic runs at 5V,I believe.

I think you wil find that most of your power is going into the video
drive (or LCD backlight) circuitry.

"Arfa Daily" <arfa.daily_at_ntlworld.com> wrote in
news:O24eo.36157$r24.2988_at_hurricane:

Thanks for the insights Jeff. All interesting stuff. These are
dedicated games machines, not based on a PC in any way. The power
supply is specced to deliver 12v at 23 amps, yes, that's twenty
three amps ...

Almost all of this is potentially going into these two processors,
so not far off 300 watts between them. No mean task shifting the
heat off them !

Arfa



what processors(microprocessors?) run at 12V?
ISTR that today's uPs run mostly on 3.3V

Most other digital logic runs at 5V,I believe.

I think you wil find that most of your power is going into the video
drive (or LCD backlight) circuitry.

--
Jim Yanik


Er no. There are no backlights. Or display processor. These are X-Box
/ Playstation type boxes. Apart from some support circuitry in IC form
- which admittedly does gobble enough power to make it run hot enough
that a degree of heatsinking to the pcb shielding via thermal pads is
required - everything goes on in a pair of very large BGA processors,
one of which is the data processing engine, and the other of which is
the graphics processing engine. It is they which make use of the 12v,
and they which gobble the amps from it ...

The power supply does have other outputs, but these are all at very
low current availabilities, so will be for support logic and maybe
some core supplies for the two processors. Trust me when I say that
the two big chips is where all the power is going, and generating heat
that needs shifting
:-)

Arfa



Odd that BGA processors are using 12V instead of logic level voltages.

I'm surprised they don't use some sort of liquid or heat-pipe plumbing to
remove all that heat. Wasn't it the CRAYs that used liquid Freon to flood
the processor cabinet to dissipate al the heat built up?

--
Jim Yanik

Jim Yanik wrote:

Odd that BGA processors are using 12V instead of logic level voltages.


Then they would need around 100A at 3.3 volts. The voltage drop
would be a big problem. I'm sure there is a DC to DC converter near the
chip, like used on computer motherboards.

I don't believe it. The winner of the power hogging consumer CPU
contest was the DEC/Intel Alpha 21364 (EV79):
http://en.wikipedia.org/wiki/Alpha_21364
which burned 155 watts. Itanium II came close with 130 watts (per
core).

On Fri, 27 Aug 2010 20:19:44 -0700 Jeff Liebermann <jeffl_at_cruzio.com
wrote in Message id: <ebug76lk13plippid57h6q6vacu8ve4om9_at_4ax.com>:

I don't believe it. The winner of the power hogging consumer CPU
contest was the DEC/Intel Alpha 21364 (EV79):
http://en.wikipedia.org/wiki/Alpha_21364
which burned 155 watts. Itanium II came close with 130 watts (per
core).

Check again.
http://ark.intel.com/Product.aspx?id=43410&processor=9350&spec-codes=SLBMX
185W! Gotta love that price as well.

You answered your own question. The AMD heatsink / quad core Phenom
II 955
Black Edition package comes with Artic Silver already applied. I'm
using
an Antec server case that has a hole and tube in the side cover.
The end
of the tube fits directly over the CPU heat sink so it draws air
directly
from the outside. In back is a pair of 120mm fans controlled by the
mainboard. If the CPU temp goes up all three fans increase
according to
the temp. Or you can set them to run at full speed all the time.
The 650
watt PSU also has a temp sensing 120mm fan. So the box is really
quiet
most of the time. But when rendering video and the CPU usage hovers
around 50% fan speed increases slightly. Video rendering with an
application that takes advantage of multi-core processors seem to
use the
most CPU percentage. I've never seen it go over 50%. Most of the
time it
doesn't go over 10%.  

--
Live Fast, Die Young and Leave a Pretty Corpse

On Aug 27, 6:09 am, Meat Plow <mhyw...@yahoo.com> wrote: <snip
You answered your own question. The AMD heatsink / quad core Phenom
II 955
Black Edition package comes with Artic Silver already applied. I'm
using
an Antec server case that has a hole and tube in the side cover.
The end
of the tube fits directly over the CPU heat sink so it draws air
directly
from the outside. In back is a pair of 120mm fans controlled by the
mainboard. If the CPU temp goes up all three fans increase
according to
the temp. Or you can set them to run at full speed all the time.
The 650
watt PSU also has a temp sensing 120mm fan. So the box is really
quiet
most of the time. But when rendering video and the CPU usage hovers
around 50% fan speed increases slightly. Video rendering with an
application that takes advantage of multi-core processors seem to
use the
most CPU percentage. I've never seen it go over 50%. Most of the
time it
doesn't go over 10%.

--
Live Fast, Die Young and Leave a Pretty Corpse

Sony Vegas software will push your processor usage up to nearly 100% and
stay there for minutes. My Phenom II 955 machine normally idles 115-120
Watts but will peak about 100 more while Vegas is rendering a file. I'm
almost tempted to try a 6 core processor to see what happens.

G²

On Mon, 30 Aug 2010 05:35:00 -0400, JW <none_at_dev.null> wrote:

On Fri, 27 Aug 2010 20:19:44 -0700 Jeff Liebermann <jeffl_at_cruzio.com
wrote in Message id: <ebug76lk13plippid57h6q6vacu8ve4om9_at_4ax.com>:

I don't believe it. The winner of the power hogging consumer CPU
contest was the DEC/Intel Alpha 21364 (EV79):
http://en.wikipedia.org/wiki/Alpha_21364
which burned 155 watts. Itanium II came close with 130 watts (per
core).

Check again.
http://ark.intel.com/Product.aspx?id=43410&processor=9350&spec-codes=SLBMX
185W! Gotta love that price as well.

I stand corrected.
http://techreport.com/discussions.x/18445
Some of the reader comments are rather interesting. Still, with any
of these "powerful" processors, a conventional air cooled machine is
going to have a very hot breath and a rather large power supply. I
just don't see this kind of power dissipation in a "dedicated game
machine". Measuring the AC mains power consumption should settle the
matter.

--
Jeff Liebermann jeffl_at_cruzio.com

"Jeff Liebermann" <jeffl_at_cruzio.com> wrote in message
news:phnn76d5fjpcls7lfscj6t40hehqnc9db4_at_4ax.com...
On Mon, 30 Aug 2010 05:35:00 -0400, JW <none_at_dev.null> wrote:

On Fri, 27 Aug 2010 20:19:44 -0700 Jeff Liebermann <jeffl_at_cruzio.com
wrote in Message id: <ebug76lk13plippid57h6q6vacu8ve4om9_at_4ax.com>:

I don't believe it. The winner of the power hogging consumer CPU
contest was the DEC/Intel Alpha 21364 (EV79):
http://en.wikipedia.org/wiki/Alpha_21364
which burned 155 watts. Itanium II came close with 130 watts (per
core).

Check again.
http://ark.intel.com/Product.aspx?id=43410&processor=9350&spec-codes=S
LBMX 185W! Gotta love that price as well.

I stand corrected.
http://techreport.com/discussions.x/18445
Some of the reader comments are rather interesting. Still, with any
of these "powerful" processors, a conventional air cooled machine is
going to have a very hot breath and a rather large power supply. I
just don't see this kind of power dissipation in a "dedicated game
machine". Measuring the AC mains power consumption should settle the
matter.

--
Jeff Liebermann jeffl_at_cruzio.com


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 ? 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.

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.

Arfa

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 ?

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.

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.

ncidentally, 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.

This is quite a bit more dissipation than the average desktop, causing
some things to be more critical.

1. The less silicon grease used, the better.

2. All heat sinks and transistor bases are NOT flat.

3. Compression pressure is important. None of the standard spring
clip CPU heat sink holders come even close to optimum.