Should we connect molex 4 pin to rx 480

cvipercviper Member Posts: 132 ✭✭
Hello should we connect 4 pin molex to our usb powered risers to our asrock h81 pro btc.currently its not recognizing it in windows 10 only on the x16 pci e.

Comments

  • cvipercviper Member Posts: 132 ✭✭
    Just connected .what does that mean
  • depadredepadre Member Posts: 10
    What PSU are you using? You need to connect that molex to your PSU
  • LogicaluserLogicaluser Member Posts: 214 ✭✭
    the mobo has Molex connectors for people who use unpowered ribbon risers.

    You have a powered USB style riser, which requires it's own direct power connection.
    It's isolated from the board, so it makes the on-mobo molex connections in your second photo unneeded.

    FYI, do not use the Molex-SATA adapter that came with riser with a RX480. Use a direct molex connection to the riser.
  • Marvell9Marvell9 Member Posts: 593 ✭✭✭

    the mobo has Molex connectors for people who use unpowered ribbon risers.

    You have a powered USB style riser, which requires it's own direct power connection.
    It's isolated from the board, so it makes the on-mobo molex connections in your second photo unneeded.

    FYI, do not use the Molex-SATA adapter that came with riser with a RX480. Use a direct molex connection to the riser.

    Um no I use SATA molexs on all three of my 480 rigs with no issues
  • LogicaluserLogicaluser Member Posts: 214 ✭✭
    Marvell9, these will easily do ~70w via the slot in their stock config, well above what a SATA power connector's tiny pins were ever intended to provide. It may work, but it's certainly not without added risk. These do draw like +3x more than a Tahiti-based card via the slot, after all.

    Although IIRC your running some 6 card rigs? so I guess it may be the best available option for a couple cards
  • SIRacer09SIRacer09 Member Posts: 246 ✭✭
    OK, I'm confused... I've got a 6 card rig with (4) R9 290 Ref and (2) RX 480 (8GB). Ever since I started a few months ago with some R9 280x and 7950s, I've used USB 3.0 powered risers. I've always connected the molex on the riser to the sata connectors on my PSUs. Is this the wrong way? I've never had any issues with them...
  • AtrocityAtrocity Member Posts: 46
    SIRacer09 said:

    OK, I'm confused... I've got a 6 card rig with (4) R9 290 Ref and (2) RX 480 (8GB). Ever since I started a few months ago with some R9 280x and 7950s, I've used USB 3.0 powered risers. I've always connected the molex on the riser to the sata connectors on my PSUs. Is this the wrong way? I've never had any issues with them...

    I never had any issues either until I was dual mining sia and eth burned 2 of those 4 pin cables. Like they literally melted so yeah I think @Logicaluser is right.
  • greenusergreenuser 50.8862°N 4.5537°WMember Posts: 439 ✭✭
    @Logicaluser SATA will do 10A i.e. 120w (each voltage rail uses more than one pin in the SATA) Your mobo may not though.

    @SIRacer09 where do you want your cards to get their power from?
    From the PSU but through the mobo to the riser? or Direct from the PSU?

    You are correct! If your card dies and pulls too much current, you may damage your power cable. No big deal. But if this happens when they are powered from your mobo, you could cook your mobo.

    So a card may be able to pull 4.5A (70w) from its PCI-e x16 edge connector... but, if you want to add a riser you might still be able pull that current through a SHORT ribbon riser but, you will run into problems with a longer ribbon or a USB3 cable due to voltage loss over distance (i.e. Volt drop per meter (v.d/m)) Therefore; you will need a power lead from the PSU (SATA or MOLEX 10A 120w) to help carry the load.

    Notice the long cables from the PSU (>0.3m) will be 16AWG while shorter cables (<0.3m) may be lighter gauge 18AWG, This compensates for Volt drop (v.d)

    Also it will depend on the quality of the PSU as to cable gauge
  • cvipercviper Member Posts: 132 ✭✭
    Hello guys.Thank you all for the help and answers.The psu is 1050W Seasonic gold standart(https://www.amazon.com/Seasonic-SS-1050XM2-1050-Power-Supply/dp/B00607JL5C).I readed from deep gougle research that this messages only concern people with not molex powered riser , so i just skipped it with "N" key and everything works now.So far the cards and the system are stable and everything is running fine.ive underclocked the cards and reduced the voltage while boosted the ram MH/s.Im mining eth only atm with 27mh/s per card.Boosted the RPM on the fans to 2500RMP(50% of total RMP) and its running at 59C in hot room wich is nice.The usb risers seems to be about 30-40 CM long.
    Not sure what to do about dual mining as some of you said that it could damage your hardware.Cables are a cheap replacement but i burn down the GPU its going to be expensive.Do you thing there is a chance to damage my hardware if i start dual mining now with 119W @card and [email protected]
    Btw even tested the system with stock settings and i was getting arround 24mh/s and 86C running temps.IT was stable and running fine for 1h test.
  • LogicaluserLogicaluser Member Posts: 214 ✭✭
    edited July 2016
    @SIRacer09 that is typical, I have a tons of rigs setup like that.

    The problem here is that the RX480 in particular draws a TON more power via the slot than does anything else in AMD's lineup going back like 5 generations, simply treating it as a drop-in replacement for a multi-card 7900/200 series rig is a disaster waiting to happen. (as @Atrocity can speak to)

    5x 7950 might only be 75-125w combined drawn through the risers, whereas 5x 480 might be 300w combined via risers

    @greenuser Link that says SATA power can handle 10A of 12V?

    Molex certainly can, but everything I've read about SATA power indicates a 1.5 amp per 12v pin maximum (the pins are much smaller)
    Oh, and 4.5A of ATX 12V is 52-56w not 70w
  • SIRacer09SIRacer09 Member Posts: 246 ✭✭
    greenuser said:

    @Logicaluser SATA will do 10A i.e. 120w (each voltage rail uses more than one pin in the SATA) Your mobo may not though.

    @SIRacer09 where do you want your cards to get their power from?
    From the PSU but through the mobo to the riser? or Direct from the PSU?

    You are correct! If your card dies and pulls too much current, you may damage your power cable. No big deal. But if this happens when they are powered from your mobo, you could cook your mobo.

    So a card may be able to pull 4.5A (70w) from its PCI-e x16 edge connector... but, if you want to add a riser you might still be able pull that current through a SHORT ribbon riser but, you will run into problems with a longer ribbon or a USB3 cable due to voltage loss over distance (i.e. Volt drop per meter (v.d/m)) Therefore; you will need a power lead from the PSU (SATA or MOLEX 10A 120w) to help carry the load.

    Notice the long cables from the PSU (>0.3m) will be 16AWG while shorter cables (<0.3m) may be lighter gauge 18AWG, This compensates for Volt drop (v.d)

    Also it will depend on the quality of the PSU as to cable gauge</p>

    @greenuser I'd like to power my gpus directly from my PSU, so how do I do that? My mind is blown, I didn't know I was doing it wrong all this time. Haha!
  • Marvell9Marvell9 Member Posts: 593 ✭✭✭
    @greenuser lol yeah this entire thread is funny
  • LogicaluserLogicaluser Member Posts: 214 ✭✭
    edited July 2016
    @SIRacer09 older cards are just fine using SATA-molex adapters for risers, it's only the RX480 risers that would benefit from Molex connection instead, what with their 2-3x higher slot power draw.

    @Marvell9 Feel free to exceed the draw for SATA power connectors if you wish, but you shouldn't be so cocky as to laugh at other people's genuine concerns. @Greenuser is incorrect in claiming 10A, the SATA power connector specification is 1.5A per pin for 4.5A of total 12v
    http://www.molex.com/molex/products/datasheet.jsp?part=active/0675810000_CRIMP_TERMINALS.xml&channel=Products&Lang=en-US

    Did you miss the guy a few posts up that mentioned his melted cables from dualmining with SIA?

    Your 6x 480 rig could very well be drawing 300-400w via it's risers at stock, far more than we GPU miners have traditionally drawn over SATA-Molex adapters. Undervolting will certainly help, as would some experimentation with those I2C commands 'the stilt' provided the other week.
  • workwork Member Posts: 2,084 ✭✭✭✭
    @logicaluser I've had melted cables and connectors more then once from a (very expensive/high-end) shitty PSU too over the years. I personally have no concerns about SATA connectors carrying enough power for risers for the RX 480s.

    Keep in mind it's actually a total of 54+22.5=76.5 watts available over a SATA connector if you consider both +12v and +5v, based on the _rated_ 1.5Amps per circuit.

    The I2C adjustments the stilt suggested are irrelevant with the latest drivers, as the driver does this for you automatically.
  • greenusergreenuser 50.8862°N 4.5537°WMember Posts: 439 ✭✭
    Marvell9 said:

    @greenuser lol yeah this entire thread is funny

    me too!


    Molex certainly can, but everything I've read about SATA power indicates a 1.5 amp per 12v pin maximum (the pins are much smaller)
    Oh, and 4.5A of ATX 12V is 52-56w not 70w

    Yes, you are right about 4.5A of ATX 12V is 52-56w not 70w :D
    Serves me right for being a smart ass :o

    Molex has 2 power pins (one 5V and on 12V pin), each can deliver 11Amps for a total of 22Amps. The other 2 pins are ground wires...

    SATA power connectors has a total of 15 pins of which 9 are power pins (3 x 3.3V, 3 x 5V, 3 x 12V). Each pin can carry 1.5Amps for a total of 13.5Amps. BUT as there is as yet no use for the 3.3V pins the effective power available to drives is only 9Amps and not 10.



    Sh*t, i used to so good at posting while drinking. I am getting old
  • josechudmjosechudm Member Posts: 63
    guys i need some advice from you, i got 4 asus radeon 470 strix edition, and a Gigabyte AM3+ AMD 970 SATA 6Gbps USB 3.0 ATX AM3+ Socket DDR3 1600 Motherboards (GA-970A-DS3P) + AMD FX 4-Core Black Edition FX-4300, FD4300WMHKBOX +Electop PCI E Express 1X to 16X Riser Card USB 3.0 Extender Cable with Power

    But according to you and several other people this wont be a safe rig, using a sata riser with these radeon 470-480

    So what do you guys suggest?

    I got one string of molex cable with 4 pins x3 unused

    should i use new risers that use those 4 pins molex cable? and connect each riser to those 3 ports?
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