Connecting Power supply to Motherboard Processor Socket


D

Dave C.

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

You've got the wrong power supply. I'd suggest you replace it with the
following:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817702010

Along with being a good brand and very high quality, it's also dirt
cheap (relatively speaking) -Dave
 
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M

mac

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
 
M

Mike Easter

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?

Yes, you can buy a 4pin to 8pin adapter, but that doesn't solve the
larger problem of figuring out whether your PS is adequate for your
needs or not. Hopefully the PS gurus in here will help you with that
question.

For background, according to what I'm reading in the wikipedia
(snippages down below at ^1^2) the 'standard' ATX 12V is the P4^1 which
you have and the 8 pin is EPS12V^2, so you could say that the 8 pin is
associated with heavier duty PSes & mobo requirements. More wires and
pins is a way of carrying more juice.


^1 ATX12V 4-pin power connector (also called the P4 power connector). A
second connector that goes to the motherboard (in addition to the main
24-pin connector) to supply dedicated power for the processor. For
high-end motherboards and processors, more power is required, therefore
EPS12V has an 8 pin connector.

^2 Power supplies built to the EPS standard include a 24-pin motherboard
power connector and an 8-pin +12V connector. The standard also specifies
two additional 4 pin 12V connectors for more power hungry boards (one
required on 700W-800W PSUs, both required on 850W+ PSUs) . EPS power
supplies are in principle compatible with standard ATX or ATX12V
motherboards found in homes and offices but there may be mechanical
issues where the 12V connector and in the case of older boards the main
connector overhang the sockets.
 
P

Paul

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
 
M

mac

Paul -

Thanks you for the outstanding explanation - it makes perfect sense. I do
in fact have two 2X2 connectors to make a 2X4. Regarding the brand of the
PSU (AGI) - It was recommended by the store where I bought all my parts.
http://www.digilinkcomputers.com/ Digilink computers. It's a Michigan
base business, which has a local tore here in town. I have bought from
them before many times and are very reputable.

My system will be (I'm assembling it this saturday - Its for home use - not
gaming).
Motherboard: GA-MA770T-UD3P AMD AM3 Socket
Processor: Phenonm II X4 945
RAM: 4 Gig DDR3
HD: 1 TB Seagate
Video: PNY Geforce 9500GT 1024 MB PCI Express
Sound: Integrated
PSU: IGA 550W
DVD RW - Liteon
USB Mouse and Keyboard

Thanks,
mac
 
M

mac

Mike,

Thank you for the reply. I discovered that the PSU has two 2X2 connectors
that combined make a 2X4. I think I'm OK.

Thanks!
mac
 
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J

John Doe

mac said:

mac

When posting, especially when asking for help, snipping text you do not
want reread, and posting in context (instead of top posting) is
desirable.
 
P

Paul

mac said:
Paul -

Thanks you for the outstanding explanation - it makes perfect sense. I
do in fact have two 2X2 connectors to make a 2X4. Regarding the brand
of the PSU (AGI) - It was recommended by the store where I bought all my
parts. http://www.digilinkcomputers.com/ Digilink computers. It's a
Michigan base business, which has a local tore here in town. I have
bought from them before many times and are very reputable.

My system will be (I'm assembling it this saturday - Its for home use -
not gaming).
Motherboard: GA-MA770T-UD3P AMD AM3 Socket
Processor: Phenonm II X4 945
RAM: 4 Gig DDR3
HD: 1 TB Seagate
Video: PNY Geforce 9500GT 1024 MB PCI Express
Sound: Integrated
PSU: IGA 550W
DVD RW - Liteon
USB Mouse and Keyboard

Thanks,
mac

Interesting. Newegg has two different models of 945, one at 125W and
one at 95W. The price is the same and yet one is lower power than the
other.

I'll assume 125W. (125W/0.9)/12V = 11.6A from 12V2

The only number I could find for 9500GT was 50W, so we could say
12V @ 4A in round numbers.

12V1 current = 0.6+1.5+0.5 + 4A = 6.6A

Total 12V current is 11.6A + 6.6A = 18.2A

Total power in watts. Mobo power is an estimate, assuming things
like a 30W chipset, four DIMMs at 2 watt apiece, plus assorted
peripheral chips on the motherboard at 1 watt and so on. There
isn't enough similarity amongst motherboard designs, to refine
the number. A couple of the other numbers here, are the
5V consumptions of the storage devices.

(12V power) + mobo&RAM + +5VSB + 5V_HDD + 5V_ODD

(12V * 18.2A) + 50W + 10W + 5W + 7.5W = 290.9W

That is an outside number, one you're not likely to
see in practice. (You certainly won't see that number while
the system is idle in the desktop.) So you're under 550W.
The question then is, whether the AGI supply is a real 550W
supply or not. I like using the reviews on Newegg, because
the bad stuff tends to show its true colors in the review
section. If the AGI product isn't reviewed anywhere, and
you can't tell what it is equivalent to, then it is
harder to judge.

Paul
 
M

mac

Paul,

That's an awesome analysis. I'll definitively keep it as an example for a
future similar calculation - I don't know if I could totally duplicate it.
I'll study it some more. I'll also do a little research on the AGI PSU. It
also has another model number HEC-550TW-TF on it . And it says RoHS
2002/96/EC. In the sticker also says Supports nVIDIA SLI & Dual PCI-E. It
does make me wonder about the quality too..

Thank you so much.
mac
 
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P

Paul

mac said:
Paul,

That's an awesome analysis. I'll definitively keep it as an example for
a future similar calculation - I don't know if I could totally
duplicate it. I'll study it some more. I'll also do a little research
on the AGI PSU. It also has another model number HEC-550TW-TF on it .
And it says RoHS 2002/96/EC. In the sticker also says Supports nVIDIA
SLI & Dual PCI-E. It does make me wonder about the quality too..

Thank you so much.
mac

So that makes it a rebranded HEC/Compucase. HEC (Heroichi) used to make supplies
for Antec, then HEC tried their hand at retail marketing. Then,
Compucase (an outfit that makes computer cases) enters the picture.
I don't know if they bought HEC or HEC bought them.

I have one HEC here, but it is a number of years old. I didn't
have a problem with it. But a lot of time has passed, and
with corporate changes, sometimes a company goes from
making its own, to contracting and buying someone
else's stuff.

There are 26 HEC/Compucase models on Newegg right now, and you
can check out the reviews on them, and see if their quality
has kept up or not. Maybe you'll get lucky, and visually
identify your model.

http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2010090058+50001446&Subcategory=58

Paul
 
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