how to identify 12V rails ?

[trx]

I've got Corsair HX620W power supply:
http://www.corsairmemory.com/products/hx.aspx

it has 3 12V rails with max current 18A each and max combined wattage 600W.

it has modular cables and connectors look like this:

null
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but, I can't find out how to connect 3 molex (or SATA power) cables to 3 different 12V rails.

I have 8 power consuming HDDs (every WD7500AAKS eats up to 30W at the spinup) and I would like to devide them on 3 different 12V rails instead of attaching them on the same one.


any ideas?

 

[John]

I would think the HX520 & 620 have similar distribution.

http://www.jonnyguru.com/review_details.php?id=28

The "official" word from Corsair was the following:

* 12V1: ATX 20+4, 4-pin +12V and 8-pin +12V
* 12V2: PCI-e 1 and first two peripheral connectors
* 12V3: PCI-e 2 and last three peripheral connectors

It gets better...

Looking at the main PCB, we only see two points where 12V leads are soldered down. One labeled 12V1 and another labeled 12V2. For fun, I put a 30A load on the 8-pin EPS+12V connector. This should have tripped the PSU. It did not, which tells me that there is no OCP limiter set for this rail. I did the same with the ATX main connector and again the PSU did not trip.

This demonstrates that if the two rails are in fact separate, there is no OCP (over current protection) on each rail. Outside of a few traces zig zagging across PCB, I couldn't find how even 12V1 and 12V2 are separate, but I'm going to give Seasonic (the OEM for the Corsair units) the benefit of the doubt and say that we seem to have two 12V rails here, neither with any kind of "limit" on them.

Originally posted by: trx
every WD7500AAKS eats up to 30W at the spinup

Is there a credible source for that kind of power usage? WD specifies Read/Write @ 8.77 Watts

 

[trx]

http://storagereview.com/WD7500AAKS.sr?page=0%2C5

http://storagereview.com/images/WD7500AAKS_peak.png

 

[Zepper]

I don't see the startup currents listed on that WD specs page, you'll probably have to find it in the detailed tech manual for the drive. I always assume nearly 2A on the +12 for startup and about 1A for the +5V.

Most split 12V rails these days really aren't - it's just a marketing fiction. Just another bad idea from your friends at Intel...

.bh.

 

[John]

trx, I said credible! All kidding aside, I find it interesting the drive draws that much on spinup from a cold start, so I sent off an email to WD for their input.

 

[oynaz]

IIRC, the drives use 5V, not 12V.
So your question is not relevant.

 

[Zepper]

oynaz,
Desktop HDDs and optical drives use both 12 and 5V lines. Notebook drives use only the 5V line.

.bh.