Title: No overcurrent using 6x 7950 and Lepa G1600 Post by: lorbas on February 10, 2014, 11:49:34 AM Some people say you can't use a LEPA 1600 with 6 cards wihtout overcurrenting the rails. I think, using undervolted 7950's, it works. Here's what I figuered out:
1x 7950 @ 1.094V / Core@1100 / Memclock@1250 draws 230W Here's the LEPA's rail layout: 12v1=20A = Motherboard ONLY 12v2=20A = CPU ONLY 12v3=max. 30A = 4x PCIe 12v4=max. 30A = 2x PCIe 12v5=max. 30A = 4x PCIe 12v6=max. 30A = 2x PCIe Sata/Molex get their 12v power from 12v4 and 12v6. First of all you attach a 7950 to rails 3-6 by using the PCIe-plugs. That way these rails draw 19A which leaves 11A headroom. Cards 5 and 6 could then be split by using either one of the red PSU's PCIe-plugs and/or one PCIe to Molex converter. So now here's what is drawn through rails 3-6 with a six card setup when using the setup mentioned above: 12v3 = card 1 and 1/2 card 5 = 345W = 28.75A 12v4 = card 2 and 1/2 card 5 = 345W = 28.75A 12v5= card 3 and 1/2 card 6 = 345W = 28.75A 12v6= card 4 and 1/2 card 6 = 345W = 28.75A Makes a total wattage of 1440W. I reserved 60W for peripharels, CPU etc. The load on rails 3-6 should be even lower since power is also drawn through the PCIe-slots so that 6x25W is drawn through rail 1 I suppose. I admit that you would be running rails 3-6 at nearly full load so be careful. Who agrees? Who does not? Title: Re: No overcurrent using 6x 7950 and Lepa G1600 Post by: InCoinsITrust on February 10, 2014, 02:17:36 PM Depens if you are overclocking those 280X, they can draw a lot of power (300W)
Title: Re: No overcurrent using 6x 7950 and Lepa G1600 Post by: Sythyn on February 10, 2014, 02:22:36 PM Some people say you can't use a LEPA 1600 with 6 cards wihtout overcurrenting the rails. I think using undervolted 7950's it works. Here's what i figuered out: 1x 7950 @ 1.094V / Core@1100 / Memclock@1250 draws 230W Here's the LEPA's rail layout: 12v1=20A = Motherboard ONLY 12v2=20A = CPU ONLY 12v3=max. 30A = 4x PCIe 12v4=max. 30A = 2x PCIe 12v5=max. 30A = 4x PCIe 12v6=max. 30A = 2x PCIe Sata/Molex get their 12v power from 12v4 and 12v6. First of all you attach a 7950 to rails 3-6 by using the PCIe-plugs. That way these rails draw 19A which leaves 11A headroom. Cards 5 and 6 could then be split by using either one of the red PSU's PCIe-plugs and/or one PCIe to Molex converter. So now here's what is drawn through rails 3-6 with a six card setup when using the setup mentioned above: 12v3 = card 1 and 1/2 card 5 = 345W = 28.75A 12v4 = card 2 and 1/2 card 5 = 345W = 28.75A 12v5= card 3 and 1/2 card 6 = 345W = 28.75A 12v6= card 4 and 1/2 card 6 = 345W = 28.75A Makes a total wattage of 1440W. I reserved 60W for peripharels, CPU etc. The load on rails 3-6 should be even lower since power is also drawn through the PCIe-slots so that 6x25W is drawn through rail 1 I suppose. I admit that you would be running rails 3-6 at nearly full load so be careful. Who agrees? Who does not? Agree, 7950 draws really low power anyway.. |