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Any Know About Computer Power Supplies?  
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Posted (7 years 4 months 2 days 3 hours ago) and read 1378 times:

Yes I have tried searching for this, every site I stumble upon seems to follow the only axiom "people don't buy drills, they buy holes."

I actually asked this question on a techie specific forum, the answers I got were watered down and were not what I asked:

What on/connected to the motherboard uses the power from the +3.3v, +5v, +12v, -12v, and 5vsb lines?

Like, I hear the CPU runs off of the 12volt line, correct? etc.


The meaning of life is curiosity; we were put on this planet to explore opportunities.
9 replies: All unread, jump to last
 
User currently offlineGkirk From UK - Scotland, joined Jun 2000, 24904 posts, RR: 56
Reply 1, posted (7 years 4 months 2 days 2 hours ago) and read 1370 times:

+3.3V = Chipsets, DIMMS, PCI/AGP cards misc chips
+5v = Disk drive logic, SIMMs, PCI/AGP cards, ISA cards, voltage regulators, misc chips
+12v = Motors, High output voltage regulators


Also you get negative voltage (-5v and -12v).
-5v is routed to the ISA bus on pin B5, thus allowing any ISA card to use the -5v supply. Also, on older floppy controllers, the analog data separator circuits use -5v supply.



When you hear the noise of the Tartan Army Boys, we'll be coming down the road!
User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 2, posted (7 years 4 months 2 days 2 hours ago) and read 1360 times:

wow, a straight answer, thank you.

Quoting Gkirk (Reply 1):
+3.3V = Chipsets

North and south bridge? Power usage then highly dependant on bandwidth or bus speed?

Quoting Gkirk (Reply 1):
+3.3V = ..., DIMMS

Type of or speed of memory relevant?

Would you happen to know what is the maximum number of watts that can be drawn from the PCI2.0+ slots?



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlineTedTAce From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 4 months 2 days 1 hour ago) and read 1353 times:

Quoting Gkirk (Reply 1):
+3.3V = Chipsets, DIMMS, PCI/AGP cards misc chips
+5v = Disk drive logic, SIMMs, PCI/AGP cards, ISA cards, voltage regulators, misc chips
+12v = Motors, High output voltage regulators


Also you get negative voltage (-5v and -12v).
-5v is routed to the ISA bus on pin B5, thus allowing any ISA card to use the -5v supply. Also, on older floppy controllers, the analog data separator circuits use -5v supply.

Woah, check out the big brains on Kirkie!!!  thumbsup 


User currently offlineGkirk From UK - Scotland, joined Jun 2000, 24904 posts, RR: 56
Reply 4, posted (7 years 4 months 2 days 1 hour ago) and read 1352 times:

Quoting TedTAce (Reply 3):
Woah, check out the big brains on Kirkie!!! thumbsup

It helps when you have a degree in Computing  Wink

Quoting Lehpron (Reply 2):

North and south bridge?

Both.

Quoting Lehpron (Reply 2):
Power usage then highly dependant on bandwidth or bus speed?

Yup

Quoting Lehpron (Reply 2):
Type of or speed of memory relevant?

Makes no difference IIRC.

Quoting Lehpron (Reply 2):
Would you happen to know what is the maximum number of watts that can be drawn from the PCI2.0+ slots?

Not off the top of my head  Wink



When you hear the noise of the Tartan Army Boys, we'll be coming down the road!
User currently offlineWSOY From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 4 months 18 hours ago) and read 1296 times:

Quoting Lehpron (Thread starter):
What on/connected to the motherboard uses the power from the +3.3v, +5v, +12v, -12v, and 5vsb lines?

+3.3V: CPU (re-regulated on-board, CPU can also draw from other supplies), logic (depending on the age of the board), semimodern RAM, earlier AGP versions, modern PCI bus;
+5V, logic (depending on the age of the board), RAM (ending in old SDRAM types) older PCI bus versions;
+12V: used to be needed for RS-232, also required for Intel-standard motherboards (with the additional 4-pin connector.);
-12V: used to needed for RS-232;
5Vsb: required for startup logic (startup button, keyboard/mouse start-up, if any).

There's also a -5V line, but that was dropped from the latest spec, and was in any case a leftover from the very earliest generation of DRAM, and therefore also present on the spec of the ISA bus.

[Edited 2007-03-25 19:33:20]

User currently offlineWSOY From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 4 months 16 hours ago) and read 1266 times:

Quoting Lehpron (Reply 2):
Would you happen to know what is the maximum number of watts that can be drawn from the PCI2.0+ slots?

I take you're asking this purely out of academic interest? I guess you'll find the answer in this document.
http://focus.ti.com/lit/ds/symlink/tps2342.pdf


User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 7, posted (7 years 4 months 9 hours ago) and read 1240 times:

First off, no TedTAce, this isn't about a TEC. After careful analysis, maintaining a thermoelectric cooler is not worth the delta temperatures.

Quoting WSOY (Reply 6):
I take you're asking this purely out of academic interest?

Just trying to figure out what I'm using, and then, what I can go up to.

My current psu specs say "quoting manual":

max's: +5Vdc@36A, +12Vdc1@20A, +12Vdc2@18A, -12Vdc@0.8A, +5VSB@2.5A, +3.3Vdc@30A;
Total +5V/+3.3V shall be less than 240W
Total +12V1/12V2 shall be less than 360W
Total +5V/+12V/+3.3V shall be less than 560W
MAX power shall be less than 630W

Voltages measured by the EMC6D103 chip on the motherboard reads:
+2.5V: 1.55V
Vcore: 1.22V
+3.3V: 3.32V
+5V: 5.20V
+12V: 12.38V

I want to know how to calculate the maximum processor overclock I can achieve without having to get a bigger power supply. I can't do that without some of the information you folks provided.

All I have is a 95W TDP Intel Pentium D, single optical combo drive, single video card (GeForce 7950GT OC'd 610/840, est. 90W), single PCI sound card (SB Audigy SE), 2 sticks of DDR2 memory, single HDD SATA.

My estimates for power so far is 280 watts, but which rails and how many amps doe I have left?



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlineWSOY From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 4 months ago) and read 1225 times:

Quoting Lehpron (Reply 7):
I want to know how to calculate the maximum processor overclock I can achieve without having to get a bigger power supply.

Your CPU will shut down due to thermal overload well before your PS runs out of power. Rest assured about it.


User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 9, posted (7 years 3 months 4 weeks 1 day 20 hours ago) and read 1209 times:

Quoting WSOY (Reply 8):
Your CPU will shut down due to thermal overload well before your PS runs out of power. Rest assured about it.

This isn't my first barbeque, just I cannot do anything with my current motherboard. Rather than spend first and complain later, I am informing myself before I drop a dime. I'm a researcher, it's what I do.



The meaning of life is curiosity; we were put on this planet to explore opportunities.
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