VLe
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Monday, December 28, 2020 1:23 AM
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Hi, I tried to search this forum and Google so hopefully this isn't a duplicate thread.
I would like to run 4 fans in push/pull as exhaust on my 3090 XC3 Hybrid and allow the GPU to control all 4 fans. The cable coming from the fan header has two in-line 4-pin connectors. Would it be safe to connect a y-splitter to each connector and then connect the 4 fans or would that exceed the GPU fan header's amp limit? I know MB usually have a 1A limit on their fan headers, but I don't know what the limit is on the GPU fan header.
Would a reasonable alternative be to connect the fans to a powered fan hub and then connect that to the GPU for the sake of RPM control? I feel like that would avoid hitting any header limits. Is there another solution for running push/pull and retaining GPU RPM control? Thanks!
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ty_ger07
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 3:25 AM
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It is definitely possible if you have some electrical splicing and insulating skills. The fans don't have to use any power from the card at all. All the fans need is the PWM signal from the card to each fan (in blue below), and 1 (and only 1!) fan needs to send tachometer signal (in green below) back to the card. The fans' 12v power and ground (in yellow and black below) can connect straight to a 4-pin molex connector for their power source. Make sure that you don't accidentally send more than 1 fans' tachometer signal back to the card, otherwise the fan control will be haywire due to clashing signals. If you use off-the-shelf fan splitters, you might have to cut the tachometer signal wire on one of the splitters in order to prevent multiple tachometer feedback signals from reaching the card. Here is a sketch I posted in this forum some time in the past. You can use your imagination about how to add 2 more fans to that schematic: Edit, fine, no imagination needed...
post edited by ty_ger07 - Monday, December 28, 2020 3:36 AM
ASRock Z77 • Intel Core i7 3770K • EVGA GTX 1080 • Samsung 850 Pro • Seasonic PRIME 600W Titanium
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VLe
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 4:19 AM
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Thanks for taking the time to reply and to diagram that out!
I was thinking of purchasing this ( and connecting it to a SATA power source and to the fan cable coming out of the hybrid kit. The seller specs 1A on each of the 10 fan channels, so the Noctuas I'm thinking of getting should be within spec. I'm not sure how the tach feedback would be handled, though...
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ty_ger07
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 4:34 AM
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This is what I use: https://www.amazon.com/Cable-Matters-2-Pack-3-Fan-Splitter/dp/B01DV1Z0WC ...Or at least something identical in appearance. I don't remember if it was the exact same brand or model. With those 2, you can control up to 5 fans, and not worry about the tach feedback issue as long as the 2nd daisy-chained one is plugged into the first one which has the green tach wire. As long as only one fan total is connected to a green wire, the fan tachometer thing is taken care of. I hope that makes sense. You can probably find a version with sleeved wires and black connectors if you don't like the appearance. I use my splitters behind my motherboard tray, so I don't have to worry about the appearance.
post edited by ty_ger07 - Monday, December 28, 2020 4:41 AM
ASRock Z77 • Intel Core i7 3770K • EVGA GTX 1080 • Samsung 850 Pro • Seasonic PRIME 600W Titanium
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VLe
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 4:39 AM
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That's very interesting... Thank you!
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glocked89
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 3:20 PM
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Running 4 nf-a12x25s in push/pull on my hybrid kit using 2 y-splitters. Works totally fine. I believe each fan is 0.15 amps
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VLe
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 3:28 PM
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Thanks for letting me know! I chose NF-P12 redux with 1,700 RPM. Just checked and the max draw is only 0.09, so splitters shouldn't have any issue... You retain full fan control? How do you feel about your temps?
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ty_ger07
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 3:34 PM
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I wouldn't recommend a splitter which doesn't have a power connector. I mean, you might not fry the card's fan header, but it is a small gamble. But there is a bigger reason not to use the card's fan header for the fans' power: power limit. These cards are very power limited and any power the fans use will reduce the power available to the GPU and affects how high the card will boost. I would recommend this: The one I posted above, or this slightly prettier version: https://www.coolerguys.com/products/evercool-fan-cable-5-pwm-fans-cb-ec-df001 Not this: https://www.amazon.com/Splitter-TeamProfitcom-Computer-Extension-Converter/dp/B07TRV6XZX Do as you wish. Both methods will work. One method is a little less messier than the other method, but the messier method is safer and can provide better overall results.
post edited by ty_ger07 - Monday, December 28, 2020 4:00 PM
ASRock Z77 • Intel Core i7 3770K • EVGA GTX 1080 • Samsung 850 Pro • Seasonic PRIME 600W Titanium
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glocked89
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 3:45 PM
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VLe Thanks for letting me know! I chose NF-P12 redux with 1,700 RPM. Just checked and the max draw is only 0.09, so splitters shouldn't have any issue... You retain full fan control? How do you feel about your temps?
Fantastic! Those should be quite quiet :p Yes I have full control and have them running on a custom curve through Precision X1. With my fan curve, I can keep it right at 50c or below with about a 400watt load. Quite satisfied with the temps actually and push/pull does make a difference. If you can stay under 60c I think the hybrid kit is worth it. Also the nf-a12x25s pull 1.68watts(0.14 amps) each at max if that matters to you.. Your nf-p12s pull only 1.08watts at max
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VLe
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Re: Push/Pull on Hybrid while maintaining fan connection to GPU?
Monday, December 28, 2020 4:14 PM
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Hey Ty_ger, you definitely make a good point regarding leaving as much power available to the GPU as possible. I have a powered fan hub coming, so that should remove the fans' power draw from the equation. I appreciate the links you shared; I'm not sure where my Molex PSU connectors have gone, but I'll keep them in mind. No SATA-to-Molex for my rig right now! :p
Glocked, I'm glad your solution is working well for you! Your results are making me feel more comfortable that I'm not wasting my time with this.
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