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The weird 4pin adapter that comes with BitFenix fans... is it safe?

post #1 of 7
Thread Starter 
I got a 200mm BitFenix LED fan in the mail today. It came with an adapter that goes from 4pin molex to 4pin fan plug. The strange part about it is that on the molex end, the two wires go into both live connectors- one into the 12v yellow wire and the other into the 5v red wire. Nothing is in either ground wire on the molex connector.

BitFenix says this will power the fan at 60% speed, or 7 volts. My electrical experience says it will either do nothing, or fry my PSU. I need to use it, but I just wanted to get your opinions before I hook it up to my rig.
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The One Rig
(16 items)
 
 
"Loading"? Lol, what's loading?
Samsung 840 PRO Series MZ-7PD256 256GB 2.5-inch SSD
CPUMotherboardGraphicsRAM
i5 6600k @ 4.0 GHz Asus Z170 Pro Gaming/Aura Asus GTX1070 O8G 16GB Crucial Ballistix @2400MHz 
Hard DriveHard DriveCoolingOS
Samsung 850 EVO 250GB HGST Deskstar 3TB Be Quiet! Dark Rock 3 Windows 10 Home 
MonitorKeyboardPowerCase
Asus PB287Q Razer Blackwidow Chroma EVGA Supernova 750 G2 CM MasterCase Pro 5 
MouseMouse PadAudioAudio
Razer Diamondback Chroma Razer Firefly Logitech Z623 Logitech Z506 
CPUCPUMotherboardGraphics
Xeon E5-2650 V3 Xeon E5-2650 V3 ASUS Z10PE-D16 WS EVGA GTX TITAN-Z 
RAMHard DriveHard DriveHard Drive
128GB of Crucial DDR4-2133 Server Memory (8x16GB) 480GB Intel 730K Series HGST Deskstar NAS 6-TB HGST Deskstar NAS 6-TB (backup drive) 
Optical DriveCoolingCoolingOS
Pioneer USA BD Drive Cooler Master GeminII S524 Rev. 2 Cooler Master GeminII S524 Rev. 2 Ubuntu 14.04.2 LTS 
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post #2 of 7
Do you really expect them to mass market a product that would rain fire down on every user's PSU?
post #3 of 7
It's fine..
post #4 of 7
Personally, I wouldn't think that BitFenix would release a product that would cause issues and potential damage to the consumers devices. I believe that the onboard fans are actually grounded via motherboard and connect with the motherboard 24pin connector which grounds to the power supply. You should be fine. The 5v Wire is for fan speed adjustments, the fan controller part of the fan and the 12v, well that's the power.
post #5 of 7
The voltage potential between 12V and 5V is 7V.

The 5V works as the current return path for the fan. Now, a buck regulator design, or descendent of it (like most ATX PSUs), can only pass current in one direction. If you try to put current through a buck regulator in reverse it will either shut down or explode.

However, if the amount of +5V current drawn exceeds the amount of current dumped into +5V, the net current going through the transistor will still be positive, and you will not have any issue.



So in short, only run a few fans at 7V and you'll be fine. If you do a ton of them, it's probably not a great idea.
post #6 of 7
Thread Starter 
Quote:
Originally Posted by beers View Post

Do you really expect them to mass market a product that would rain fire down on every user's PSU?

Like I said, I just wanted to make sure before I stuck this in my $2000 computer. BitFenix did mass-market a fan which doesn't hardly fit in 80% of cases (I had to cut out a couple mounting tabs on my HAF912's front panel to get it in.)
Quote:
Originally Posted by CM Phaedrus View Post

The voltage potential between 12V and 5V is 7V.

The 5V works as the current return path for the fan. Now, a buck regulator design, or descendent of it (like most ATX PSUs), can only pass current in one direction. If you try to put current through a buck regulator in reverse it will either shut down or explode.

However, if the amount of +5V current drawn exceeds the amount of current dumped into +5V, the net current going through the transistor will still be positive, and you will not have any issue.



So in short, only run a few fans at 7V and you'll be fine. If you do a ton of them, it's probably not a great idea.

Alright, I'll give it a shot. Hopefully 7V isn't as loud as it is on 12V but still moves some air.
The One Rig
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Samsung 840 PRO Series MZ-7PD256 256GB 2.5-inch SSD
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i5 6600k @ 4.0 GHz Asus Z170 Pro Gaming/Aura Asus GTX1070 O8G 16GB Crucial Ballistix @2400MHz 
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Samsung 850 EVO 250GB HGST Deskstar 3TB Be Quiet! Dark Rock 3 Windows 10 Home 
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Asus PB287Q Razer Blackwidow Chroma EVGA Supernova 750 G2 CM MasterCase Pro 5 
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128GB of Crucial DDR4-2133 Server Memory (8x16GB) 480GB Intel 730K Series HGST Deskstar NAS 6-TB HGST Deskstar NAS 6-TB (backup drive) 
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The One Rig
(16 items)
 
 
"Loading"? Lol, what's loading?
Samsung 840 PRO Series MZ-7PD256 256GB 2.5-inch SSD
CPUMotherboardGraphicsRAM
i5 6600k @ 4.0 GHz Asus Z170 Pro Gaming/Aura Asus GTX1070 O8G 16GB Crucial Ballistix @2400MHz 
Hard DriveHard DriveCoolingOS
Samsung 850 EVO 250GB HGST Deskstar 3TB Be Quiet! Dark Rock 3 Windows 10 Home 
MonitorKeyboardPowerCase
Asus PB287Q Razer Blackwidow Chroma EVGA Supernova 750 G2 CM MasterCase Pro 5 
MouseMouse PadAudioAudio
Razer Diamondback Chroma Razer Firefly Logitech Z623 Logitech Z506 
CPUCPUMotherboardGraphics
Xeon E5-2650 V3 Xeon E5-2650 V3 ASUS Z10PE-D16 WS EVGA GTX TITAN-Z 
RAMHard DriveHard DriveHard Drive
128GB of Crucial DDR4-2133 Server Memory (8x16GB) 480GB Intel 730K Series HGST Deskstar NAS 6-TB HGST Deskstar NAS 6-TB (backup drive) 
Optical DriveCoolingCoolingOS
Pioneer USA BD Drive Cooler Master GeminII S524 Rev. 2 Cooler Master GeminII S524 Rev. 2 Ubuntu 14.04.2 LTS 
MonitorKeyboardPowerCase
Seiki 39" 4K TV Logitech K740 EVGA Supernova 1600 T2 Phanteks Enthoo Luxe 
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post #7 of 7
Quote:
Originally Posted by Drpillz624 View Post

... I just wanted to make sure before I stuck this in my $2000 computer ...


As Phaedrus has explained the +12V/+5V trick is a basically unhealthy botch. You can safely lower the fan speed with a cheap extension with resistor:


If you are handy you can even scavenge a 50~100Ω resistor from some old or broken electronic equipment, and solder it on the fan +12V wire to lower its speed, at zero cost.
HAL-9011
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HAL-9011
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CPUMotherboardGraphicsRAM
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Hard DriveHard DriveHard DriveOptical Drive
OCZ Vertex 4 128GB OCZ Vertex 2 120GB WD Caviar Black 1TB LG DVD-RW 
CoolingCoolingOSOS
Noctua NH-D14 Accelero S1 R.2 + 2x NF-F12 Se7en x64 Se7en x32 
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Antec TP-650W CM HAF 912 + 
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Overclock.net › Forums › Cooling › Air Cooling › The weird 4pin adapter that comes with BitFenix fans... is it safe?