Dual PSU Problems, 2nd PSU clicks and stops...

I'm updating this first post with the information I've gathered throughout this thread:

As the number of hard drives in my system has increased, I decided to buy a new Coolermaster Stacker case, along with a 2nd PSU. The plan was to move my hard drives onto my 620w modular Enermax (which I bought extra cables for), whilst my motherboard, processor and graphics were to be powered by a new FSP 700w.

I used the dual PSU Y-plug included with the case, which appears to just turn on the 2nd PSU at the same time the 1st one is being turned on.

However, the first time I tried to use it, the 2nd PSU (Enermax) would power on for perhaps a second with the fan revving up etc, but would then shut off. Consequently, my BIOS detected no drives. I then tried unplugging all of the modular leads and the PSU stayed on when booted. After this, I tried plugging in one at a time.

After experimenting with different combinations, I was able to ascertain tha the PSU worked with up to two 7200rpm drives, or one Raptor + 7200rpm drive. It would not work with anything more, such as both of my Raptors at once. When I plug in more than this, I hear a repeated clicking noise, and none of the drives seem to be detected. On the plus side, it doesn't seem to turn itself off until I get to perhaps 5 drives.

As recommended in this thread, I swapped the PSUs around. Consequently, the Enermax was once again powering the motherboard etc. To my surprise, this worked fine. The Enermax is currently powering all of the drives at once, though I obviously want to take this burden off of it as soon as possible.

Update: I tried connecting green to black to power on the PSU with just the Raptors connected. The drives would rev up for about 3 seconds then turn off, rev and turn off, just repeating.

It thus appears my PSU requires a minimum load on the ATX12V... Read on.

have you tried swapping the psu's around? ie fsp one powering the hdd's and enermax on the mobo and stuff?

Unfortunately I can't do that; the FSP only has 4x SATA connectors, which is insufficient for the number of hard drives I have.

I just don't see how/why the Enermax would appear to be struggling or experiencing a fault when powering more than one drive? :(

Ah.. makes things a bit harder eh. Have you tried with less hard drives connected on the enermax. Like remove a few and try booting up?

I've been experimenting with combinations, and have been able to boot one Raptor on its own. The same is possible with the other drives, but more than 2 (even on different cables) results in the clicking etc.

I've read that drives consume alot of power on startup, but I'm thinking that wouldn't apply to you seeing as you've got a whole dedicated PSU just for the drives....

We'll just have to wait for others to chime in with some advice.

Some PSUs require a certain amount of load to start up, for example my HEC PSU converted to lab bench top PSU will only start with 1A load on the 3.3v rail, sticking a 5W resistor into a orange wire (3.3v) to a ground wire on the ATX connector allowed it to start.

I think you need to slightly 'load' one of the motherboard power rails, my bet is on the 3.3v rail as many PSUs do.

I just tried powering the graphics card as well as the hard drive. The PSU turned off after around 10 seconds. :(

I should probably add that the FSP is performingly solidly at the moment.

maybe faulty psu? People have had a few problems with the latest Enermaxes. There's a guy on the forums who had to RMA his in the first week. Not that they aren't good but you may have a bad one of the bunch.

Ok just to update, I've been doing some more testing. It would appear that I can run up to 2 hard drives at once, including a Raptor, but no more than 3, and no more than 1 Raptor.

This is certainly beginning to sound like a RMA job. However, Scan no longer seem to stock this model... Does anyone know what the procedure is here? Would they provide me with a voucher to spend the £100 I bought this for on another PSU?

Not sure, I think they'd offer a similiar make/model/psu if your one is discontinued.

The plot thickens...

I just took apart the PC and reconnected with the Enermax as the motherboard and processor power source. It was able to power the Raptors etc without problem. Furthermore, the 2nd PSU was able to run other drives simultaneously. :S

I therefore come back to you DDY; would you be kind enough to give me some more info as to how I can find out which rail needs this load, and what that translates into (in terms of what I should plug in etc).

I still need to get the Enermax working for the hard drives, as I have bought extra modular cables specifically for this purpose. One thing I don't understand is why it would run one or two drives but not more? If it were a minimum load problem, would this not be indicitive of something wholly different? :(

Updated with some new 'findings'...

From the Enermax website:
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Except for the maximum output limitation, there is also the minimum load requirement of the PSU. (The minimum load requirement of the ATX12V form factor is about 15W.) If system loading fail to meet PSU specified DC minimum load requirement, the PSU might not be able to maintain the DC voltage output stability. In this situation, the PSU will stop working in prevent system damage.

This occurs more with the dual core processors with energy saving design introduced after Q3 2006. Due to the very light CPU +12V power draw at boot-up stage, it fails to meet the +12V minimum output loading condition of the PSU, therefore, the PSU will turn off automatically for protection. Once you add a HDD or ODD, this will meet the PSU minimum load requirement, and everything will work fine.
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Surely then, 8+ hard-drives should do the trick?

Quote:

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Originally Posted by WLC-1989

Surely then, 8+ hard-drives should do the trick?

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Aha, the 8+ hard drives doesn't do the trick. The ATX12V connector is the 4Pin (P4) connector that goes into your mobo that powers the CPU. Theres also an EPS12V 8-Pin connector which is common on most Intel boards (dunno if its the same for AMD) Because you have that cable not under load the Enermax thinks it's damaging the system so it shuts off. You should try taking out the FSP P4 or EPS12V connector and plugging the Enermax one in. That might solve your problem but lets hope the FSP PSU doesn't mind. Although I'm not sure if it's okay to power the CPU with one and the the Mobo and GFX card and other parts with the other. If you could find a similiar cable like the one that links the 24 pin mobo connectors on both PSU's together like you said in your first post but for the P4 or EPS12V connector then maybe you wouldn't need to swap them. It's just your PSU choice and setup which caused it to fail.

Unfortunately, I tried mixing the two (ATX12V from the Enermax, 24 pin from the FSP) and the PC shuts off almost immediately.

Does anyone know of a means to get around this? Perhaps a specific adaptor that allows one to utilise the ATX12V, perhaps converting it to a molex or SATA connection?

http://www.maplin.co.uk/Module.aspx?ModuleNo=98948

Basically, I need something like this but working in reverse. Can anyone suggest such an adaptor? If not, does anyone know if it's possible to construct the adaptor I need, or would it require specialist parts?

The quickest way to do that, buy a 4-pin 12v power extension like this, chop the plug end of the extension off and crimp (or solder) that end to a 4-pin 12v/5v socket like this.

Thanks for your reply DDY. Would the method you propose definitely:

1) Be sufficient for powering a hard drive... I.e. Is there a chance that the voltage/amps involved would be too high/low? I'm unsure if these are PSU constants or vary with different power connectors.

2) Be sufficient to bypass the PSU's minimum load protection, thus allowing it to be used to power the other drives too?

Finally, with the two items you suggested; would you be kind enough to give me some advice on which wires of the ATX12V plug into which of the 4-pins of the molex connector?

I appreciate all the info you're giving me; hopefully I'll have his PC up and running by the weekend. :)

There would be plenty of power for multiple HDDs from the 4-pin 12v connector. However, a hard drive also requires a 5v input, for this you need to do 'adapt' to the cable I suggested above.

Note the HDD power connection pinout here, most importantly note the 3 wires, yellow (12v), red (5v) and black (ground). The yellow 12v wires should lead to the 4-Pin 12v (motherboard connector) and the 5v should come from any 5v source e.g. another 4-Pin 14v/5v connector as seen in this crude MSPaint diagram which took over 4 seconds to draw.

http://img.photobucket.com/albums/v6...ssssssssss.gif

This should be enough to start the PSU, if it isnt; try hooking it up to a DVD drive or similar, in fact you should do this first, then try the HDD.

Thanks so much for your help, I'll buy those parts tomorrow and get back to you on how it went.

I just constructed the adaptor and unfortunately it didn't work; the PSU still switches off. :(

Do you have any other recommendations? Perhaps something for the 24-pin?