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Connecting fans to the motherboard

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April 20, 2011 10:04:02 PM

Just built my first rig and things are running well. Thanks again TH community for all the advice for the noob.
I have two PSU connection questions that are nitt picky but hey once you build it, slowly tweaking is half the fun.

1) Most of the fans in my case are powered by molex connectors. I would love to plug them into my motherboard ((MSI P67A-GD65 for new sandbridge chip) so I can control them. Right now they are working fine connected to the same serial/daisy chained? wire from the PSU (OCX sleathxstream 700w) which has several molex connectors that come off the main wire at spaced intervals and a thin four pin female plug labeled p7 at the end. What is this end plug. In my head I feel like it should connect to the sys fan slot on the motherboard but those are 3 pin. If this has nothing to do with that, is there a molex to 3 pin fan adapter. I am not sure it matters or will be worth it but i am curious to know why this plug is at the end of this molex cord.

2) I tried to leave room for upgrading by getting a MB with enough slots that I can run two graphics cards in the future and by getting a PSU that I thought should be able to handle it. Right now I am running a single ASUS ENGTX570. This takes both the 6 pin PCI-E connectors. I assume it need both or it would not have the plugs for both. SO do I need both plugs and is there any way if I get a second card I can use this PSU that only has these two plugs.

Thanks all
adam
a b B Homebuilt system
a b V Motherboard
April 20, 2011 10:37:15 PM

1) I think this four pin connector is a floppy power connector (does it look like this? As the name suggests it's the power cable that is used to power floppy disk drives and occasionally some other devices. It's pretty much a legacy power connector.

I had a quick google for molex to 3 pin but couldn't find exactly what you wanted. I'm sure it exists though. I wouldn't go out of your way though. Just stick to what is working. If a few months it's really bothering you then just buy some new super awesome, super quiet fans with 3 pin connectors. :) 

2) I've already posted elsewhere today stating that system builds should be multi GPU from the start or never. When that 570 starts to run a bit slow just sell it and pick up a next gen card. You won't have issues with your PSU doing this, you'll get better performance gains and you'll pay less in electric bills.
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a b V Motherboard
April 20, 2011 10:39:35 PM

1) The 4-pin connector you describe (P7) is for any floppy drives you might have installed. Do NOT plug them into the fan connectors on the motherboard, unless you feel like replacing it!

2) There are adapters that convert a 4-pin Molex connector to PCI-E power connectors. You should be able to use those, as long as your power supply can supply the amperage necessary for the cards.

Casey
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a b B Homebuilt system
a c 208 V Motherboard
April 21, 2011 3:18:20 AM

1. You can buy adapters which is kind a messy with the big bulky molex plastic thingies hanging all over the place ....

http://www.frozencpu.com/products/1093/cab-09/3-pin_to_...

or ya can do what I do and make it neat and pretty:

http://www.frozencpu.com/products/1828/ele-180/FrozenCP...
http://www.frozencpu.com/products/1821/ele-173/3-Pin_Po...
http://www.frozencpu.com/products/3836/too-07/FrozenCPU...

http://www.frozencpu.com/products/1845/ele-196/14_Blue_...
http://www.frozencpu.com/products/3726/slv-25/FLEXO_PET...

Last two items just make it look perty :) 

As for the 4 pin connector, look here for an explanation (floppy):

http://www.antec.com/Believe_it/connectors.php?ProdID=2...

2. I do a lotta builds with provisions for adding a 2nd GFX card in the future .... while I wouldn't recommend picking one up 2 or 3 years down the line, it's a nice way of extending system life at least 12-18 months when short of capital at build time. I find the timing works best when ya build a box spending what ya can in spring .... the2nd card can be added come fall when the new generation cards are released and the cost of that card you bought 6-8 months ago goes rapidly south.

I wouldn't worry about ya electric bill hit from the 2nd card. With a max draw of 212 watts (25 idle) .... assuming an average usage of 30 hours per week .... 1/3 of that at peak.

25 watts x 20 hours = 500
212 watts x 10 hours = 2120
Total = 2.62 kw-hrs x $0.10 x 4.3 weeks per month = $1.27 per month .... say $4.00 even at 4 times the usage.

The ideal build today us twin 560 Ti's (900Mhz version) .... in SLI, they score just 1.3 % below twin 570's. So your left w/ two choices:

a) There should be two molex to PCI-E adapters in your Asus box (each PCI-E connector requires two molex connections to PSU)..... Im not a fan of this alternative.

b) upgrade your PSU to an XFX Black Edition 850 or something else w/ enough connectors.
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April 28, 2011 1:20:03 AM

Best answer selected by madmonkeymusic.
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