Help! PCI-E power connector question

[mdnightman]

I thought PCI-Express power connector should have 6pin, but my
motherboard MSI 975X has 4-pin socket (look like molex type on back of
a DVD drive) for PCI-E x16. Can I simply connect the molex 4pin power
cable to it?

Thanks!

 

[RussellS]

I thought PCI-Express power connector should have 6pin, but my
motherboard MSI 975X has 4-pin socket (look like molex type on back of
a DVD drive) for PCI-E x16. Can I simply connect the molex 4pin power
cable to it?

Thanks!

-------------------------------------------
Your board may have a 4-pin Molex plug in order to supply extra 12V to the
board with dual card configurations, but the 6-pin PCI-Express power
connector is not to be plugged into a motherboard, but, rather, to be
plugged into a PCI-Express graphics card that requires it. Some cards have
this power plug, while other may not need a separate power plug or may use a
standard Molex or floppy power connection. Depends upon the particular
card. Most higher-end PCI-Express cards do have this power plug on them,
while a lot of the mid-range or lower end cards may not require it.

Hope this helps,
Russell
http://tastycomputers.com

 

[mdnightman]

Yes, your answer helped, but I'm still confused about the following:

From the motherboard manual "the ...12V power connector is used to

provided power to the PCIEX16 graphics card"
Pin definition
1 5v
2 2 gnd
3 3 gnd
4 12 v
(again, the connector looks like molex type)

From the Power supply unit

4-pin Molex:
Pin 1 12v
2 com
3 com
Pin 4 5v

So looks like pin 1 and 4 are reverse of what is needed. I have no idea
what power wire is used to plug into this connector on the motherboard.

 

[RussellS]

Yes, your answer helped, but I'm still confused about the following:

provided power to the PCIEX16 graphics card"
Pin definition
1 5v
2 2 gnd
3 3 gnd
4 12 v
(again, the connector looks like molex type)


4-pin Molex:
Pin 1 12v
2 com
3 com
Pin 4 5v

So looks like pin 1 and 4 are reverse of what is needed. I have no idea
what power wire is used to plug into this connector on the motherboard.

----------------------------------------
The Molex plug on the motherboard above the top PCI-Express graphics card
slot is there just to supply extra voltage stability from the board to
higher-end graphics card configurations, but can be used even if you have a
low end card. The Molex plug is keyed so that a standard Molex connector
from a power supply cable can only go in one way. You only need the
separate 6-Pin PCI-Express power cable from the power supply plugged
directly into your graphics card if your particular card requires it. As
previously mentioned, some cards have this, some don't.

Russell
http://tastycomputers.com

 

[WooHoo2You]

The Molex plug on the motherboard above the top PCI-Express graphics card
slot is there just to supply extra voltage stability from the board to
higher-end graphics card configurations, but can be used even if you have
a low end card.

My Asus A8n-sli Prem has that plug, but the manual vaguely only mentions
it's use if two graphics card are being run in SLI. Is there any help/harm
in connecting it to the PSU if only one video card is being used?

--
WooHoo2You

Athlon 3800 X2
4 x 512 MB 3200 DDR 400
a8n-sli Premium
GeForce 6800 256 MB PCI-e
Sound Blaster Audigy 2 Value
200 GB SATA HD
160 GB SATA HD

 

[RussellS]

My Asus A8n-sli Prem has that plug, but the manual vaguely only mentions
it's use if two graphics card are being run in SLI. Is there any
help/harm in connecting it to the PSU if only one video card is being
used?

--
WooHoo2You

Athlon 3800 X2
4 x 512 MB 3200 DDR 400
a8n-sli Premium
GeForce 6800 256 MB PCI-e
Sound Blaster Audigy 2 Value
200 GB SATA HD
160 GB SATA HD

---------------------------------------------
Shouldn't be a problem having it connected without 2 cards, but why bother
if the system is stable without it connected? You have one less power cable
to route. maximizing airflow and minimizing cable clutter. I would
recommend connecting it, however, if you later add a second card into the
mix.

Russell
http://tastycomputers.com