Computer Audio Asylum: P24 current measurements by Bertel Music servers and other computer based digital audio technologies.

For Sale Ads FAQ / News / Events

Posted by Bertel (A ) on May 4, 2009 at 12:57:52

In Reply to: cMP - the open source high-end Memory Player posted by cics on December 30, 2007 at 05:42:01:

I'm in the process of going "all battery" for P24 too (P4 done), so in order to right-size the respective power lines I considered it a good idea to do a few measurements (just as Dave and Mark have done on P4). Thought I'd share if anyone else is interested - brought a few interesting insights, at least to me.

Current setup: Almost "standard" recommended cMP2 setup, i.e. Gigabyte GA-G31M-S2L, E7200, 1GB Mushkin EM2-6400 [superior to ValueRam and HyperX], Lynx AES-16 [will go Juli@ w/ external 3.3V PS next week], cPlay 2.0b23 SSSE3, all optimizations incl. Minlogon done - did I forget anything...?). Measurements done with Antec Earthwatts 430 for convenience, picoPSU showed same results.

All BIOS optimizations done. CPU host frequency at 150 MHz, SPD at 2.00, Mushkin RAM timed manually at 3-3-3-7, CPU GTLREF at 0.566V, CPU Voltage at 0.76875V (it's a shame but I can't get any lower, no way system would boot then...). CPU-Z reports Core Voltage to be at 0.752V. Core Speed is 900MHz, Bus Speed is 150MHz, FSB is 600MHz.

-------------

"Special" power rails:

* 5V StandBy:
- When PS turned on before pressing Power Switch: 170mA
-> During operation (idle / playback): 50 mA

* Power_Good:
- No current could be measured with my rather "rough" multimeter -> seems that since this is a signal line, it is sufficient that just the voltage is provided with some very low current, certainly below 50mA, according to my measurements below 10-20mA, but 5V provided

* Power_On:
- Switches from 5V to 0V at startup, so not relevant here

* -12V:
- As little as ~10mA during operation

NOTE: Most important (and for me quite surprising) :
All of the above can be TURNED OFF COMPLETELY during operation, they are NOT NEEDED during playback (at least in my [recommended] setup)! I ran all of the aboce through a switch, and I could turn them off at any time even during music playback without any adverse / negative effects. Didn't expect that... ;-)

So the "relevant" lines to take care of come down to:

-------------

"Regular" power lines:

* 12V:
- Starting at 180mA at startup, quickly coming down to 140mA and staying at that level during idle and playback

* 3.3V:
- I had supposed that being the "main line", but it isn't - starting at ~300mA and staying constant at that level during idle and playback

* 5V:
- Now that's the real thing... Starting right off at 3 - 3.2A (!), going up to 3.6 - 4.2A during boot up - and breaking off as soon as cMP is loaded... This 5V line is so volatile, changing current so quickly and swiftly that it seems to not tolerate my rather "slow" multimeter - couldn't get the system up and running with the multimeter phased in - will retry with caps in place :-)
Nevertheless, the learning is: tis is the rail with the BIG draw at ~ 3.5 to 4.5A (more precise measurements to follow when caps are in place)

-------------

Hope you find this as useful as I do - did that the best I could, please notify me of any flaws or errors I made, comments highly appreciated.

Cheers,
Robert

This post is made possible by the generous support of people like you and our sponsors:

Signature Sound

[ Signature Sound Lounge ]