1st time computer building/wiring question

Thank you in advance for everyone's help!

I have (at least for now) a few questions. First, my componenets:
ASRock Exteme 4 Gen3 mb
I5-2500k cpu
Zalman CNPS9900MAX-B 135mm cpu fan
XFX 6950 2gb gpu
G.Skill Ripjaw X (1866) 16gb RAM
Corsair HX650 80+brze. modular psu
Crucial M4 128gb SSD
WD cav blk 1tb 7200rpm HDD
w/ peripherals and Win 7 prof

1) I am having difficulty connectin this board properly. With ALL componenets connected EXCEPT the SSD and case fans I am able to start this beast up with no issues. As soon as I connect EITHER the SSD or case fans nothing happens when I press the power button.

2) I already fried one MB and had to RMA it after attempting to daisy chain 4 case fans to one 4x MOLEX power cord. The cord connects directly to the psu, has 4x MOLEX connectors AND a 4pin connection at the end of the cord...I tried to plug this into the CHA_FAN1 pins on the mb! I'm assuming this is when people with experience are cringing...I'm learning slowly... I did this thinking the fans would be speed controlled, where is my flaw?

3) As a side note, This mb has Virtu for switching between the on-board graphics and the discrete gpu I also have installed. To take advantage of this do I need to separate DVI connections, one from the mb to my monitor AND one from my discrete gpu to my monitor??? I am having trouble understanding the auto switching.

Thanks for your help and hopefully you're not laughing at my ignorance too much!!
7 answers Last reply Best Answer
More about time computer building wiring question
  1. Best answer
    Item 2 - you made a big error. The wires coming out of the PSU with 4-pin Molex connectors on them do NOT EVER connect to the mobo. The 4-pin Molex connectors are to provide power to IDE-type devices like HDD's, optical drives, etc. They also are used often to provide full power directly to fans, etc, but they can NOT control fan speeds - they only can run a fan at full speed unless the fan itself has some speed adjuster. On the same set of wires is another smaller type of 4-pin connector that is used to power a 3½" floppy drive if you have one - this connector is almost useless for anything else, and it certainly does NOT go anywhere on the mobo.

    If you want to control case fan speeds by the mobo, the fans in question must be plugged into one of the mobo's SYS_FAN pinouts. NOTE that these are power OUTPUTS from the mobo. They are NOT inputs to the mobo from the PSU. That's how you blew the first mobo - by putting power from the Molex lines into the SYS_FAN port of the mobo.

    Most mobos have two SYS_FAN pinouts. Sometimes only one of these is speed-controlled by the mobo, sometimes both. Each is designed for only one fan to be connected. BUT if you do some wire splicing, you CAN power up to TWO case fans from each SYS_FAN pinout. It is usually considered that each pinout can handle the heavy momentary start-up current for two fans, but not more. If you choose to do this, whether you are using 3-pin or 4-pin fans, check the fan wiring diagrams for wire color codes. Do NOT splice together the wires for the fan motor speed signals from the two fans - leave one of these wires not connected to anything. But do splice together the matched wires from each fan into one connector to plug into one SYS_FAN pinout. For example, IF you were working with 3-pin fans, you would connect both reds together near the connector on the end, both blacks together, and only one Yellow wire connected to the connector. Wiring color codes for 4-pin fans are different from this.

    If you want all your fans to run full speed all the time, you can supply power to them from Molex 4-pin connectors direct from the PSU. You can get simple adapters that convert a 4-pin Molex to a 2-pin fan supply connector. In this case, there will be no speed signal fed to the mobo, so your mobo will never know what the fan speeds are. Molex outputs have a much higher amperage available than mobo SYS_FAN pinouts, so you can use adapters to connect several fans to one Molex output from the PSU.

    So you understand, the mobo does control of the CPU cooling fan via the CPU_FAN pinout, and of the case fans via the SYS_FAN pinouts. Each of those pinouts is the power source for the fan. In the case of 3-pin fans, this is accomplished by varying the voltage supplied on the +VDC line (red wire to the fan) from 0 to 12 VDC max. In the case of 4-pin fans the system is a little different. The Ground and +12VDC lines are that way all the time, and the fourth line is a special PWM signal. Inside a 4-pin fan case is a small controller chip that uses the PWM signal to control the flow of current from the +12VDC line though the fan. BOTH types of fan also have a speed signal line on Pin #3 of the connector (Yellow wire for 3-pin fans). This signal is a series of pulses (2 per revolution) generated inside the fan motor and fed back to the mobo via this line so it can be monitored. It is not actually used for speed control - speed control is based on temperatures measured with dedicated sensors, and accomplished by varying either the voltage or the PWM signal. But the fan speed signal can be displayed for you. Also, for the CPU fan, some mobos check it as an extra precaution - if it fails (indicates no fan turning), that type of mobo will send out an alarm beep and shut down the system very quickly (not waiting for the CPU temp to rise too far) to protect the CPU from disastrous overheating with failed cooling. The mobo has several features to protect the CPU and ensure cooling, so it usually is wise to connect the CPU cooling fan to this mobo pinout and not directly to the PSU via a Molex connector.

    Re: Item 1, I don't know why you cannot get it to work with the SSD plugged in. Certainly if you did that at the same time as having the Molex line connector plugged into the mobo SYS_FAN pinout, it would not work, but that has nothing to do with the SSD.

    Your SSD is set up to connect to the mobo just like a SATA drive. This means it has two connectors for cables. One is wider - 15 pins - and you plug into that a power supply connector from the PSU designed for it and other SATA devices. The other is narrower - 7 pins - and you connect this by a small ribbon cable to one of your mobo SATA ports. Assuming you are using the SSD as your boot device, you probably want to connect it to the first SATA port of your mobo.
  2. Paperdoc, thank you! I assumed the small 4 pin connector at the end of the 4x molex from the psu was to control speeds (ie. feedback loop/sensor). Now I feel dumb but your explanation makes perfect sense, very detailed. So for my board, 2 fans will have spd control due to the 4pin connection to the mb and the other two (now that I've looked at it) will have spd control via a manual switch/turn knob. Simple!

    I AM using SATA 6gb/s connections for the SSD and the connections you mentioned are exactly what I have set up. The SATA3 connections are the first SATA ports on the mb so it works out well.

    Thanks again for the help. I will continue to try to figure out the SSD issue.

    If anyone can help answer item(s) 1 or 3 I would appreciate it!
  3. I'm not sure what you mean about the other two fans' speed controls. Do you have a separate manual speed control system available, like a panel with knobs? Or, did the fans come with attached little 3-position switches or something? Or, as I suggested, you could splice wires from two fans together into one connector and plug the pair into one of the SYS_FAN pinouts, then do the same with the other two fans. I spoke above of color coding for 3-pin fans. Here's a link to the 4-pin common color codes:

    Note the way the pinout and fan connector are built physically. You can always connect a 3-pin fan to either a 3- or 4-pin pinout. And the other way - you can plug a 4-pin fan into either. In all cases there is only one way to do this because of the plastic tongue sticking up behind pins 1-3. Also not that in all cases, pin #1 is Ground (Black on 3-pin and 4-pin), Pin #2 is +12VDC (Red on 3-pin with varying voltage, usually Yellow on 4-pin with fixed 12 VDC), Pin #3 is the speed pulse signal line (Yellow on 3-pin, usually Green on 4-pin). This is the one I said should NOT have two fan's wires spliced together. The fourth pin is only used when you have both a 4-pin fan and 4-pin pinout to connect it to. That is the one with the PWM signal.

    If you plug a 3-pin fan into a 3-pin port, or if you plug a 4-pin fan into a 4-pin port, they will work as originally designed. But what happens when you mix? A 3-pin fan plugged into a 4-pin port will work, usually at constant full speed with no speed control, because the Pin #2 of a 4-pin port is always at +12 VDC. BUT some mobos have options (manually set in BIOS or automatic) that will convert to making the 4-pin port behave like a 3-pin port (with varying voltage on pin #2) when a 3-pin fan is connected to it. On the other hand, if you plug a 4-pin fan into a 3-pin port, it works just like a 3-pin fan. The fan gets no PWM signal to use, but its does receive varying voltage on Pin #2 and that accomplishes speed control.

    Plugging your SSD into one of the SATA 6.0 Gb/s ports is the right way. I don't understand how its use prevents the mobo from starting up, though. Are you sure you are using the right power supply connection to the SSD? But IF it will boot, I suggest you go into BIOS Setup and check whether you need to Enable that port - maybe not if it's already Enabled by default.

    I know nothing about point 3, so I'll refrain from baseless speculation and hope someone else who knows something can provide guidance.
  4. I wasn't clear, sorry. After looking further, 2 of the fans DO have a manual spd control switch. No splicing needed. I'll simply run the other two at full spd. I'm ready to get this thing up and running. If I need/want to mess with BIOS for spd later (if possible) I will.
    As for the SSD, I'm not sure the likelihood, but it's possible the port isn't enabled by default. I'll try other ports for initial boot. Still waiting on my RMA/d mb so it'll be a few days.

    Thanks for the education and quick replies.
  5. Just passing...

    @ Paperdoc - excellent replies and info, spot on!
  6. Thanks for kind words, both of you.
  7. Best answer selected by bsturdy.
Ask a new question

Read More

Power Supplies Components