Max cards for 750W PSU

[imtav]

Currently, my rig has 750W PSU.  With 3 cards running 100%, power draw at the wall is 590W.  The cards I'm using are RX470 4GB, and in GPU-Z the power usage for each card shows as 95-105W while I'm mining.

I'm wondering if I'm able to add another GPU, increasing wattage by ~105W, making my rig run at ~695-700W on a 750W PSU?  Is this trying to put too much load on the PSU?  I know basic mathematics say it's ok, but I don't know enough about PSUs to know if it is reasonable of me to expect my PSU to be under 700W load 24/7.  Thanks for the help!

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[philipma1957]

Currently, my rig has 750W PSU.  With 3 cards running 100%, power draw at the wall is 590W.  The cards I'm using are RX470 4GB, and in GPU-Z the power usage for each card shows as 95-105W while I'm mining.

I'm wondering if I'm able to add another GPU, increasing wattage by ~105W, making my rig run at ~695-700W on a 750W PSU?  Is this trying to put too much load on the PSU?  I know basic mathematics say it's ok, but I don't know enough about PSUs to know if it is reasonable of me to expect my PSU to be under 700W load 24/7.  Thanks for the help!

no.



do you want the long explanation?  


here goes the  95-105 is a software number  not a real number


105+105+105 =  315  lets say  you are a 90% psu  315 /90% =  350 at the wall

so  you said  you pull   590 at the wall   that is 240 watts for your setup

if you have an insanely jacked cpu  it is 135 watts =  and you are crazy to use it.

most likely     your 3 cards are pulling 450 at the wall  or even 480

a fourth card would then bring you  to

 590 + 150 =  740  or

590 + 160 =  750


now lets say  you have a 90% psu  it means you are sending 750 x 90% = 675 into  the  unit


675 out of 750  is a true 90% draw  on your psu   which  is never recommended for atx gear.

if you want to run 4 cards you will need a better psu  or clock and volt the four cards lower then you are doing.



Of blow me off  run the four the way you say  and see if I am wrong or right.

your gear not mine.

[isoneguy]

Adding on to whatever phillipma says(he's more experienced than I)...

You don't want to run your PSU past about 80% continuous load(we're talking 24/7/365).

Higher than that drastically reduces it's lifetime and causes strange problems like power loss/OS shutdowns.

Your equipment will vary a little bit in power usage and when it spikes you want a little room.

I'd suggest a 1000w psu for a 4 card build, it will power them and a 5th card...maybe 1050ti or 750 ti for your primary display.

The 470's are 120w (average), they will pull more than that and less than that depending on the situation. The 6+2 pin plug will allow for about 300w of draw.(but you'll melt something maybe hehe)

Technically your 750w psu would work...but you wouldn't want to throw more than about 600 continuous watts through it. You might notice that on higher power cost algorithms your system would shut down.

Alternatively you can use a second PSU to supply power to the pci-e ports on your card.

[imtav]

Thanks for the quick answers, guys. Should save me some headache from being naive.
I'll start on rig #2 and get a higher PSU for that one.

[isoneguy]

If you're building multiple rigs, then you can use a secondary power supply to just power the cards.

You just plug the secondary power into the cards pci-e ports and turn it on before your computer...You can use a huuuge power supply to power multiple rigs this way...and just use tiny PSU's to power the computer.

Also...you're best off sticking to 3 or 4 470's per rig.

[Elder III]

I use an EVGA 1300 watt PSU to power both of my 6 x 470 rigs. With a little bit of undervolting I can have it using as little as 820 watts at the wall mining ZEC or as much as 980 watts at the wall mining ETH + DCR. I would be ok with a good 1200 watt PSU for 6 x 470s, but this particular EVGA is a nice deal and gives a little extra room for peace of mind.

[deadsix]

Currently, my rig has 750W PSU.  With 3 cards running 100%, power draw at the wall is 590W.  The cards I'm using are RX470 4GB, and in GPU-Z the power usage for each card shows as 95-105W while I'm mining.

I'm wondering if I'm able to add another GPU, increasing wattage by ~105W, making my rig run at ~695-700W on a 750W PSU?  Is this trying to put too much load on the PSU?  I know basic mathematics say it's ok, but I don't know enough about PSUs to know if it is reasonable of me to expect my PSU to be under 700W load 24/7.  Thanks for the help!

As Phil said, if 3 cards are already at 590W for you, your cards are drawing 160W atleast. Adding another card would get the total to 750W, which may run but is not recommended at all. On a 750W PSU aim to consume no more than 600W in the long term.

Now, I do have several 5 card rigs that have been running on Corsair 750W Gold PSU's for 8 months problem free, but all my cards are heavily undervolted/underclocked.
Each card consumes 55-60W (GPUZ) and 100W at the wall producing 26mh/s.

If you want to push your cards to 28-29mh/s though, a 750W PSU wont cut it, because power consumption goes up exponentially as you overclock.

[philipma1957]

Currently, my rig has 750W PSU.  With 3 cards running 100%, power draw at the wall is 590W.  The cards I'm using are RX470 4GB, and in GPU-Z the power usage for each card shows as 95-105W while I'm mining.

I'm wondering if I'm able to add another GPU, increasing wattage by ~105W, making my rig run at ~695-700W on a 750W PSU?  Is this trying to put too much load on the PSU?  I know basic mathematics say it's ok, but I don't know enough about PSUs to know if it is reasonable of me to expect my PSU to be under 700W load 24/7.  Thanks for the help!

As Phil said, if 3 cards are already at 590W for you, your cards are drawing 160W atleast. Adding another card would get the total to 750W, which may run but is not recommended at all. On a 750W PSU aim to consume no more than 600W in the long term.

Now, I do have several 5 card rigs that have been running on Corsair 750W Gold PSU's for 8 months problem free, but all my cards are heavily undervolted/underclocked.
Each card consumes 55-60W (GPUZ) and 100W at the wall producing 26mh/s.

If you want to push your cards to 28-29mh/s though, a 750W PSU wont cut it, because power consumption goes up exponentially as you overclock.

also sometime a overclocked pushed card goes  runaway  it resets  and basically maxes say it was pulling  140-160 pushed  with hard clocks  all of a sudden it pulls 180-190 till it over heats  and if you psu was pushed hard the rig shuts down.



@ op

I try to never use a card at 80 percent of its max.  I shoot for 70% so I card listed at 150 tdp I try to never let it go over 95 watts/  The software numbers from gpu-z  are okay  but low.

I try 1 card at idle and check the entire rig on a kill a watt  say   or 30 watts  plus check gpu-z say 7 watts for the card

  I  then mine with the rig and I check  kill  a watt     say 190 for the rig  plus  check gpu-z  say  110 watts for the card

at the meter  I went up 160 watts  at the gpu-z  I went up 103 watts   so I know the gpu-z is off

[lqulong]

Currently, my rig has 750W PSU.  With 3 cards running 100%, power draw at the wall is 590W.  The cards I'm using are RX470 4GB, and in GPU-Z the power usage for each card shows as 95-105W while I'm mining.

I'm wondering if I'm able to add another GPU, increasing wattage by ~105W, making my rig run at ~695-700W on a 750W PSU?  Is this trying to put too much load on the PSU?  I know basic mathematics say it's ok, but I don't know enough about PSUs to know if it is reasonable of me to expect my PSU to be under 700W load 24/7.  Thanks for the help!

I'm mining eth with 5 rx 470 4gb and 750w Raider Silver PSU, 141mhs and 684w at the wall.