I ran 6x7970 on rosewill 1300 watt, but...
1. I mined bitcoin, not scrypt.
2. I undervolted the core (but overclocked it at the same time, probably evens out)
3. I underclocked RAM
I -think- it used about 1450 watts at the wall (i have kill a watts), which factoring in 89% efficiency at 100% capacity for 80plus gold, is 1290 watts DC.
Topic: 5x Gigabyte 7970 on a 1300w PSU...Is this possible? (Read 2789 times)
OP, it may if you're willing to undervolt the cards and lower the core clocks, probably hex-editing the bios.
How to know?
Take a look at how many Amps the PSU provides in the 12V rail. Below only applies to single rail PSU's, I don't know how to balance when it has multiple rails.
For each card
1) Plug one in, undervolt, optimize hashrate.
2) In Gpu-Z, select the 2nd page and see the Vccd In value. See how many Amps it is getting from the 12V rail. Look out for peak demands and when do they happen. Start/stop cgminer a few times to see those peaks.
Plug 3 already cards and do step 2) again. See if the cards Amp demand peaks at the same time. If not, with 3 cards you can already extrapolate to 5. Add the amp values of those 3 cards together (or pick 3x the most consuming card value), multiply by 1.66 x 1.2 (for some extra safety). If this value is higher than what the PSU provides, don't risk it.
How to know?
Take a look at how many Amps the PSU provides in the 12V rail. Below only applies to single rail PSU's, I don't know how to balance when it has multiple rails.
For each card
1) Plug one in, undervolt, optimize hashrate.
2) In Gpu-Z, select the 2nd page and see the Vccd In value. See how many Amps it is getting from the 12V rail. Look out for peak demands and when do they happen. Start/stop cgminer a few times to see those peaks.
Plug 3 already cards and do step 2) again. See if the cards Amp demand peaks at the same time. If not, with 3 cards you can already extrapolate to 5. Add the amp values of those 3 cards together (or pick 3x the most consuming card value), multiply by 1.66 x 1.2 (for some extra safety). If this value is higher than what the PSU provides, don't risk it.
You can use one CM V1000 to power these 5x 7970's... I am pretty sure this PSU can do that... I had 10 rigs with 5x 7950 each wich have V1000 psu and work fine... Also nice thing is that this PSU has 8x 6+2 connectors and to power fifth card is easy... Also it has 2x 8 pin connectors for CPU cable and you can connect additional PCIe cable to one connector on PSU wich you wont use in other circumstances...
I have (5) 7950's split between (2) PSU's - A 1275 Watt Thermaltake handles (3) PSU's and the MotherBoard, 750 Watt for the other (2). BOTH PSU's are running at about 75% of rated capacity... They are also connected to (2) different 15amp circuits. No Overheating of PSU or Household wiring.
Will it power the cards? Yes, barely.
Will it power the cards AND an attached system? Not likely.
Will it power the cards AND an attached system? Not likely.
It is barely. Don't do this.
Thanks for the input guys!!
My scrypt rigs are 4 x GV-R797OC-3GD without hard drive, and all non-essentials shut off on the motherboard, and they are just about maxing out my Antec HCP 1200w PSUs. I agree with darksoft here. Without undervolting, I would either add another power supply for the GPUs or get a bigger one to run everything.
I had 5x HD5870's at 950MHz on a 1200W Antec with no problems.
Might be okay with the GHz editions (From what I understand they use less power?)
Might be okay with the GHz editions (From what I understand they use less power?)
Either get a bigger one or add another... you're looking at appx 1250 watts of GPUs there at stock voltage.
Does any one know if a single 1300 watt rosewill will power 5 7970 gigabyte GPU's?
running 1042 gpu and 1500mhz clock
running 1042 gpu and 1500mhz clock
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