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In Reply to: RE: Need you to test current draw when display monitor is off. Also 2 more devices to disable! posted by cics on June 08, 2010 at 06:19:27
Set gdrv off in device manager but there was no change in current consumption. 1394 was not present. Tried enabled in BIOS caused BSOD....I made a mistake in my previous current measurement, there was acutally no current reduction on the 5V line. I was trying to do two tests at the same time - I put a battery as buffer in the wrong position causing erronous reading.
The following pix help understand the actual current consumption from the ATX P24.
GA H55M-UD2H defalut BIOS (9x133) (device on, no chip was removed)
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GA H55M-UD2H BIOS optimised (9x100)in CMP
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GA H55M-UD2H BIOS optimised CMP@96K
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GA H55M-(D)2H BIOS optimised CMP@96K (2 video, 1 sound, 1 network, 1 IDE chip, 2 regulators were removed)
Now it is clear that removal of the chips will reduce 12V and 3.3V current consumption.Further measurement confirmed that the 2 DVI-HDMI convertors are actually driven by the 3.3V directly from the ATX P24(I thought it would be easy to cut off the supply by desoldering the small chokes which turn out to be capacitors), the sound chip via a regulator from 12V direct and the network chip also by 3.3V by not directly from the ATX P24.
Edits: 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10 06/13/10Follow Ups:
Thanks, great to see how optimisations reduce power across different voltage lines. To summarise:
- default = (12v@0.32A, 5V@3.88A, 3.3V@0.860A) = 26.1 watts
- GA H55M-UD2H BIOS optimised (9x100)in CMP = (12v@0.28A, 5V@2.027A, 3.3V@0.698A) = 15.8 watts
- same as 2 at 96k = (12v@0.28A, 5V@2.241A, 3.3V@0.714A) = 16.9 watts
- same as 2 at 96k (mobo modified) = (12v@0.18A, 5V@2.226A, 3.3V@0.430A) = 14.7 watts
Interesting to see 5V drop is low compared to 12V & 3.3V lines when doing mobo mods. From your extreme mobo modification post, 5V line drives: RAM, H55 chipset, QPI Link, CPU PLL & ITE/Fan/etc.. Gcore and video chips take power from 12V & 3.3V lines. 5V line is most critical supply. Could a simpler mod be done that just provides clean 5V line from linear PSU or battery?
I was wanting to see if video chips on mobo are affected when the actual LCD display monitor is off. Disabling "gdrv" will not switch off display - its an unneeded device driver in Windows. I installed Windows with default BIOS hence I got to see "1394...". In your case enabling it after installation and in cMP mode will cause BSOD.
As far as possible linear supply in place of PWM PS is concerned, the 5V line is no longer critical. The concerns are large current supplies for the QPI (@1.1V) and possibly the CPU(@0.7V). At such low voltage, normal 3 terminal regulator circuit cannot work. A work around is to use a negative voltage to generate low voltage.
Heat disspation is also a concern which is assocaited with the raw DC voltage. A 6V battery supply or 5V power source would be to high as the regulator would dissipate 13W and 12W of heat respectively - a waste of energy and case temp wiould rise. A Low dropout regulator such as LT108X together with a low raw DC voltage, say 3V(or 3.3V Lithium Battery packs), would appear optimial.
I will build two low voltage regulators to test the QPI and CPU.
Your current approach is superior. I'm looking for an easier way to get say 80% of benefits. Critical chain is:
RAM > QPI link > H55 chipset > PCI or USB
These components all share 5V line. What I'm thinking of is a 5V replacement supply at P24 connector. Possible?
Please elaborate more on your idea of a 5V replacement supply at P24 connector. Do you mean replacing the ATX 5V with a linear regulated 5V supply?
I'm think of an idea to use the P24 3.3V to feed a QPI linear regulator, presuming that an ATX PS is to be used. The 3.3V line has very light current loading. By doing so, the P24 5V will be greatly relieved and the interference between the QPI load and Ram etc would be greatly reduced.
Edits: 06/14/10
Do you mean replacing the ATX 5V with a linear regulated 5V supply?
Yes. This would power the main audio streaming/signaling chain. Other components including CPU have a secondary role.
Using 3.3V line for QPI is very interesting and would reduce 5V load significantly.
Hi Jack!
What is the current consumption of the CPU (socket P4) at the last configuration (GA H55M-(D)2H BIOS optimised CMP@96K (2 video, 1 sound, 1 network, 1 IDE chip, 2 regulators were removed - I don't see the pci audio card ??? ))?
Hi, No P4 12V measurement was taken last time, but it should be 0.46A - 0.18A = 0.28A.
For 0.46A ref. http://www.audioasylum.com/forums/pcaudio/messages/7/74498.html The P4 and P24 12V lines were combined for measurement.
This time P24 12V alone measured 0.18A.
Thanks Jack! Continue the experiments.It is very useful.
Regarding the sound card, I was using a USB DAC.
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