mac said:
Question regarding connecting the Processor Power adapter to a Gigabyte
GA-MA770T-UD3P AMD AM3 Socket (Phenom Processor). The motherboard come
with a 2X4 socket ATX_12V_2X4 (8 pin). My Power supply does not have any
2X4 connectors. It has a 2X2 12V for the Processor (4 pins). Do I have
the worng PSU? Can I buy an adapter?
Here is the link for the Motherboard:
http://www.gigabyte.us/Products/Motherboard/Products_Spec.aspx?ProductID=3096
My Power Supply is an AGI 550W AGI-U550UB
http://www.leadertechusa.com/product_overview.asp?item=AGQCBAB721
Thanks, Mac
If you look in the user manual, on page 22, the table for the ATX12V connector,
tells you which holes a 2x2 connectors goes in. A 2x2 connector can be used
with the 2x4 motherboard connector. Pins 3,4,7,8 take the 2x2, and the shape
of the nylon shell ends, helps ensure the correct alignment. (So does the
location of the clamp on the connector.) If you wish to further verify you're
doing it right, make sure the yellow wires on the 2x2, are contacting the
"+12V" pins listed in the following table.
ftp://download.gigabyte.ru/manual/mb_manual_ga-ma770t-ud3p_e.pdf
Pin No. Definition
1 GND (Only for 2x4 pin 12V)
2 GND (Only for 2x4 pin 12V)
3 GND <--- black wires go here 3,4,7,8 for 2x2
4 GND <--- black wires go here 3,4,7,8 for 2x2
5 +12V (Only for 2x4 pin 12V)
6 +12V (Only for 2x4 pin 12V)
7 +12V <--- yellow wires go here 3,4,7,8 for 2x2
8 +12V <--- yellow wires go here 3,4,7,8 for 2x2
The connector family used on motherboards, is called Mini-fit Junior by the
original manufacturer. The pins take maximum currents related to both the
wire gauge used, and the number of adjacent pins. (That is why the 24 pin
connector has a lower current rating than the 2x2 connector.) The pins on
the 2x2 could be rated anywhere from perhaps 6 amps per pin to 10 amps per
pin. We'll assume 6 amps for a conservative answer.
There are two yellow wires on the 2x2 connector. That is a total of 12 amps
of ampacity (room for current flow). 12V * 12A = 144 watts. The Vcore
converter on the motherboard, converts that power source to a much lower
voltage. The Vcore converter might be 90% efficient. (I use that number,
purely to illustrate the concept, and I don't look that number up for
every motherboard I read about.) On the output of Vcore, we have
144 watts x 0.90 eff = 130 watts at the load, which is the CPU.
It means we can power a 130 watt processor, using a 2x2 connector. If
you check the tables of processors, there aren't too many which
exceed 130W. (The Phenom II x4 965 is an exception, at 140W.)
Now, if you're an overclocker, and you overclock the processor by 50%,
then that will use, at minimum, 50% more power (and perhaps a bit more).
So if you overclock a 130W processor on your motherboard, you'd want
a 2x4 connector on the power supply.
Using adapter cables, from 2x2 to 2x4, serves no purpose. It moves
the "burn point", to where the adapter connects to the power supply.
So don't even think about adapters. The main benefit of power adapter
cables, is for those situations where the motherboard is too far
from the power supply.
*******
The quality and capabilities of the power supply are a separate issue.
It is one thing, for the cables and pins to have room for 12 amps to
flow. The power supply has a rating label on the side of it, and
the 12V1 and 12V2 ampere ratings, tell you whether in fact, the
power supply can even achieve those peak current flow levels, before
conking out.
Rewriting the spec from the leadertech page
3.3V @ 32A, 5V @ 38A, 12V1 @ 18A, 12V2 @ 17A, -12V @ 1A, +5VSB @ ???
<-- 240 watt max ---> <--- ??? watt max ---->
<--------------------------550 watt max --------------------------->
The combined 12V rating in watts or amps is important, as sometimes
there is a lower combined limit, than the individual ratings. I assume
the 5VSB is at least 2 amps, and is usually between 2 and 3 amps.
2 amps should be enough, unless you're charging a lot of USB toys
off +5VSB.
12V2 is used solely by the processor. That doesn't look like a limitation.
If you had a 140W Phenom, (140W/0.90) / 12V = 13 amps. That would be
within the 17 amp limit.
The Leadertech documentation suggests there may be two 2x2 connectors.
Check to see if they "hinge together" to make a 2x4 connector. You
may in fact have a 2x4 connector, and it simply isn't assembled.
(My power supply has a connector like that. It is a 2x4 that splits
in half, to make a couple of 2x2 connectors. I use the 2x2 on mine,
as my processor is 65W.)
Other 12V loads, would go on the 12V1 output. 0.6A per disk drive.
1.5A per CDROM (only while media is spinning in the tray). Fans
are approximately 0.5A total estimated. A video card is the single
largest consumer, and they can range into the couple hundred watt
range. For example, a low end 9600GT might be 12V @ 5A.
If you had a single one of those, it would be 0.6+1.5+0.5+5.0=7.6
amps from 12V1. In that example, 7.6 amps loading is less than
the 18A limit. You then add the 12V1 and 12V2 currents, 13 + 7.6
equals 20.6 amps, and see if you've exceeded the combined 12V
power or current rating.
You can also do a "total watts" calculation. It would be better
if you posted your planned hardware, such as video card, than
for me to make up more fake examples.
Is AGI a good brand of power supply ? I can only find
reference to your supply on the Leadertech site, or on
some Chinese languages sites. No idea who actually
makes it.
Good luck,
Paul
