How to connect a 6 pin to X1800 card

nTesla · Mar 13, 2007

I've recently bought an X1800XT refurbished card, but it came bare. I've ordered a separate molex to 6 pin cable.

I wanted to find out whether I need to connect the two molexes to the PSU or just one? (On my X800gto I only connected one)

I would appreciate it if anyone who owns an x1800xt can let me know how yours is connected to the power supply.

Many thanks!

smokie mcpott · Mar 13, 2007

theres only one plugin for a sixpin

nTesla · Mar 13, 2007

smokie mcpott said:
theres only one plugin for a sixpin

No I meant the molex side. The cable I'm getting is a 6 pin to 2 molex.

My question is whether I need to connect the 2 molexes to the PSU or just one?

nTesla · Mar 13, 2007

Heres a pic:

BobcatDan · Mar 13, 2007

Two should be better, from separate rails (separate wires from the PSU, otherwise there's no real difference). That's how I would do it anyway.
Dan

Edit: My reasoning, I believe most good PSU's have multiple 12V converters (from 120v AC), so if you plug your card into two different molex connectors (presumably two different converters) you will be less likely to overdraw the PSU which would undervolt your card possibly damaging it.

smokie mcpott · Mar 13, 2007

oh, i have some of those...
you need to plug them both in, as each one supplies 3 wires

and Dan, separate plugs doesnt mean separate rails..

BobcatDan · Mar 13, 2007

smokie mcpott said:
oh, i have some of those...
you need to plug them both in, as each one supplies 3 wires

and Dan, separate plugs doesnt mean separate rails..

That's true, not all PSU's have multiple 12V rails. My point is that to plug in two molex connectors on the same group from the PSU does nothing. And if you have multiple 12v rails, they are going to be on different groups (group meaning the line of molexes sharing the same wires, no idea what the technical name is).

This is the same reason why you shouldn't put anything else on the group that's attached to your card, unless it's hooked to multiple groups (then you really have no choice).
Dan

g0dM@n · Mar 13, 2007

i feel like hooking up two diff rails to one another doesn't sound safe... i just don't understand why these 6-pins have two molex connectors on 'em...

if you want, you could also pick up a Y-adapter for molex... i may have extras myself..

BobcatDan · Mar 13, 2007

g0dM@n said:
i feel like hooking up two diff rails to one another doesn't sound safe... i just don't understand why these 6-pins have two molex connectors on 'em...

if you want, you could also pick up a Y-adapter for molex... i may have extras myself..

That's a good point, hadn't thought of what might happen. Especially if it's everything 12V in the case is hooked up, could cause a lot of noise in the signal. I dunno, then again some cards have two molex connectors on them, so there's got to be a reason...
Dan

g0dM@n · Mar 13, 2007

o0Dan0o said:
That's a good point, hadn't thought of what might happen. Especially if it's everything 12V in the case is hooked up, could cause a lot of noise in the signal. I dunno, then again some cards have two molex connectors on them, so there's got to be a reason...
Dan

unless it has to do with decreasing gauge (thus increasing area of wiring)... maybe they're afraid that one molex plug would cause the wiring to get hot, but two molex plugs wouldn't... and since the 6-pin has 6 wires in it it's already covered for increasing wiring volume... i hope that makes sense.

the ground doesn't have to be as thick, so the 6-pin is probably taking one yellow (+12v), one red (+5v), and one black (ground) from each molex plug... 3 wires times two equals the total 6 wires on the 6-pin pci-e connector... if you hook up ONE molex wire to the 6-pin I guarantee it will still work, but the wiring leading to that one molex plug may get hot or have too much resistance...

I could be completely wrong, but that's my best guess...

BobcatDan · Mar 14, 2007

g0dM@n said:
unless it has to do with decreasing gauge (thus increasing area of wiring)... maybe they're afraid that one molex plug would cause the wiring to get hot, but two molex plugs wouldn't... and since the 6-pin has 6 wires in it it's already covered for increasing wiring volume... i hope that makes sense.

the ground doesn't have to be as thick, so the 6-pin is probably taking one yellow (+12v), one red (+5v), and one black (ground) from each molex plug... 3 wires times two equals the total 6 wires on the 6-pin pci-e connector... if you hook up ONE molex wire to the 6-pin I guarantee it will still work, but the wiring leading to that one molex plug may get hot or have too much resistance...

I could be completely wrong, but that's my best guess...

I don't think the molex would get that hot, but cards with duel molex connections might do it to keep the circuits on the board from getting too hot.
It's probably just a gimmick.
Dan

Edit: I just looked up some power consumption numbers, and the hungriest of cards seem to eat about 75-85 watts, which any 12V rail should be able to supply, so I stand corrected. Also, I read (can't confirm) the 6 pin PCI-e is rated to 75W.

g0dM@n · Mar 14, 2007

o0Dan0o said:
I don't think the molex would get that hot, but cards with duel molex connections might do it to keep the circuits on the board from getting too hot.
It's probably just a gimmick.
Dan

Edit: I just looked up some power consumption numbers, and the hungriest of cards seem to eat about 75-85 watts, which any 12V rail should be able to supply, so I stand corrected. Also, I read (can't confirm) the 6 pin PCI-e is rated to 75W.

I think the hungriest cards eat a lot more than 75-85watts... I thought the x1900 cards hit around 200w...

but in any case the card doesn't get all of its power through pci-e power connectors... also gets power from the slot.

BobcatDan · Mar 14, 2007

Sorry, I meant through a molex or PCI-e 6-pin.
Dan

nTesla · Mar 14, 2007

Thanks for the replies and interesting thoughts. I'm still waiting for the cable so will try it out later on.
I also checked and noticed on my x800 there is only two cablse coming out of the pcie (black and yellow) and leads yto the molex and then a split molex comes off that molex. So I think I will need to plug both molexes for the x1800 - probably/definietly uses more juice than the x800.

g0dM@n · Mar 14, 2007

nTesla said:
Thanks for the replies and interesting thoughts. I'm still waiting for the cable so will try it out later on.
I also checked and noticed on my x800 there is only two cablse coming out of the pcie (black and yellow) and leads yto the molex and then a split molex comes off that molex. So I think I will need to plug both molexes for the x1800 - probably/definietly uses more juice than the x800.

not sure, but i think i said it in an earlier post... basically, the pci-e plug for this x1800 gets one +12v, one +5v, and one ground (total of 3 wires) from each of the two molex... thus being 6 wires to the 6-pin pci-e... the x800 only uses one +12v and one ground (and maybe one +5v - not sure...).

largon · Mar 15, 2007

nTesla,
There's 2 molexes (= two 12v wires) in the adapter because one 12v wire might not be enough for such a power hungry card. The whole connector with three 12v wires is rated for 75W, meaning each wire is rated to deliver 25W.
1 wire -> 25W
2 wires -> 50W
3 wires -> 75W

It's highly recommended to plug both molexes.

g0dM@n,
There is no 5v wire in a PCIe 6pin plug nor should there be one. If there was one the 5v and 12v would be connected on the card, you'd likely end up with a dead card.

g0dM@n · Mar 15, 2007

largon said:
nTesla,
There's 2 molexes (= two 12v wires) in the adapter because one 12v wire might not be enough for such a power hungry card. The whole connector with three 12v wires is rated for 75W, meaning each wire is rated to deliver 25W.
1 wire -> 25W
2 wires -> 50W
3 wires -> 75W

It's highly recommended to plug both molexes.

g0dM@n,
There is no 5v wire in a PCIe 6pin plug nor should there be one. If there was one the 5v and 12v would be connected on the card, you'd likely end up with a dead card.

Well, then... I stand corrected... I shoulda fished through my stuff and pulled one out before I posted... though I was at work probably at the time I said something stupid like that...

but still... I'M AWESOME!!!

nvidiaOCmaster · Mar 15, 2007

g0dM@n said:
but still... I'M AWESOME!!!

The wire that came with my X1900GT only had 3 pins, 2 of which were 12V and the other was a ground. You don't need to plug in both, just one. Trust me, im 1337

g0dM@n · Mar 15, 2007

nvidiaOCmaster said:
The wire that came with my X1900GT only had 3 pins, 2 of which were 12V and the other was a ground. You don't need to plug in both, just one. Trust me, im 1337

x1900gt may be different... some cards require all 6pins of the pci-e to be filled...

nTesla · Mar 15, 2007

Thanks for the info guys.

I've used it with both molexes and a single plugged in. don't seem to make any difference though.

How to connect a 6 pin to X1800 card

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