L7 630W - how do i tell the PCI-e rails apart?
So i got myself this shiny nicey PSU, and i have this GTX295 to be powered by it. Now, it consists of two PCBs each 150W powerful, one of which draws some power from mainboard through PCI-e slot (up to 75W), some from a 6-pin connector (up to 75W). Another PCB has no direct connection to mainboard and pulls up to 150W through an 8-pin connector.
I'm reading mr. Stefan's post here: http://www.be-quiet.net/forum/showth...CM-information
The PSU having two rails, and the GPU being so highly asymmetric, i was thinking whether it might trip protection in normal use.
Worst case of rail 1:
60W - 3 SATA drives
75W - PCI-e power through mainboard
150W - PCI-e power 8-pin
While the second rail only need to feed a 65W CPU and a 75W 6-pin connector to the GPU.
To illustrate what i mean, if the two PCI-e power leads where swapped, PSU rail 1 would carry 75W less and rail 2 75W more, providing for pretty much equal maximum load.
In worst case, rail 1 carries thus 285W or 23A, apparently well under the 30A limit... And yet, i wonder whether there's any possible problem - or benefit - from one or other particular arrangement.
And then, i can't find the slightest hint to tell the leads coming from the PSU apart, they don't seem to have any different markings, which of them belongs to each rail. So, is there a sneaky way to tell them apart, and does it even matter which is which?
The PCIe 3/4 Connectors are connected to the +12V2 rail. Since there is only one actual +12V Voltage inside the PSU, it doesn't really matter how you connect your components to the PSU. As long as it doesn't swich off under heavy load, everything is fine.
Today i went reassembling my PC in a shiny new enclosure, and noticed that it's easy enough to tell the rails apart. I know it's a been a while since i opened this thread, but want to share this for the benefit of anyone else who might run into the same question, and maybe for Stefan's benefit too
The connectors are not marked, so there is no way to tell which pair is "3/4" from connector alone.
However, the wires themselves are marked consistently. Pure yellow 12V wire is the rail that goes to ATX 20+4 and to disk drive plugs. The other rail has yellow 12V wires with a thin blue line on them, this one goes to the P4 CPU power plugs. If you look at the both PCI-e strands of cables, one has the plain yellow wires, and other has yellow wires with a thin blue line, corresponding to wire markings on the other strands.
This time over, i decided to tuck away the PCIe power strand which is shared with CPU, and try to run the GPU just from the one shared with the disk drives. I might report if i get the protection to trip anyhow, but a couple benchmarks suggest it's likely to be fine.