# HP z400 with nVidia GTX-470 -- not enough power



## jaytechman (Sep 15, 2004)

I have an HP z400 workstation that comes with 475W of power and -- believe it or not -- the power supply is "custom" and can't be replaced with an ATX power supply that's larger! (At least, not unless I can "maybe' get away with making a home-made adapter to rewire the power cabling to the system board: http://www.tomshardware.com/forum/285762-28-z400-requires-rewiring-system-board-power.) 

I bought an nVidia GTX-470 and am anxious to utilize the CUDA-enabled capabilities that Adobe Premiere Pro CS5 takes pretty remarkable advantage of. 

However, the GPU says it should have a "minimum of 550W of power." 

As I said, the z400 only has 475W and it apparently can't be increased (at least not without the "possible" mod mentioned above, which I don't even know if I can do or not -- a Corsair forum admin -- who spells out he is not a Corsair employee -- said NOT to do it unless HP will "guarantee" me the system is fully compliant with the ATX 2.01+ standard, which their techs are totally unable to find any information about). 

So, now I have to ask two questions, please:

1. Any idea where to find an after-market power supply for the HP z400 that will work properly in the machine and give me the added wattage? I have searched the web and nothing at all has come up as yet.

2. What happens if I try to use the GPU with the power supply that came with the machine? Will it "maybe" work okay? Is it a question of "It will either work fine or not at all, and you can only find out by trying?" Or, is it "very risky" in that I could seem to be working fine but then unexpectedly experience data corruption? (Which of course could also mean OS corruption and thus a massive amount of time re-installing everything.) 

Note that I want to put a total of five SATA 7200 drive into the machine, too, run by an LSI 8888ELP controller card. 

Also note that I did a partial test so far. I tried to boot the machine with the GPU installed and it did go into a boot screen successfully. I haven't taken it past that yet since there is no OS even installed on the machine yet (and I don't want to risk problems right off the bat.) 

Note that with the existing 465W power supply I do have connectors for the two PCI-Express power connectors that have to go onto the GPU. (One is achieved with a PCI-Express connector coming out of the power supply, and one is achieved with an adapter that came with the GPU that converts two molex plugs to one PCI-Express connector, which I hope is okay.)

Thanks!

Jay


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## Tumbleweed36 (May 14, 2005)

jaytechman said:


> I have an HP z400 workstation that comes with 475W of power and -- believe it or not -- the power supply is "custom" and can't be replaced with an ATX power supply that's larger! (At least, not unless I can "maybe' get away with making a home-made adapter to rewire the power cabling to the system board: http://www.tomshardware.com/forum/285762-28-z400-requires-rewiring-system-board-power.)
> 
> I bought an nVidia GTX-470 and am anxious to utilize the CUDA-enabled capabilities that Adobe Premiere Pro CS5 takes pretty remarkable advantage of.
> 
> ...


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## jaytechman (Sep 15, 2004)

Thanks, but believe me this power supply is custom. A standard ATX power supply doesn't match up with the mounting holes, but more than that the specs indicate that it's custom. And when I did plug in a standard ATX 750W power supply (after deciding to use tape to hold it in place) it wouldn't work. The machine wouln't even turn on. See that link above that shows the pin-configuration on the system power plug isn't even standard ATX. Custom power in this machine. Proprietary.


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## jaytechman (Sep 15, 2004)

But, here's an idea. What if I leave the original power supply in the machine, and then separately I use a separate 750W modular PSU (which I just happen to have on-hand) outside of the machine and run two PCI-Express power cables from that to the GPU?

An Adobe hardware guru suggest that it "should" work just fine.

What do you think?

Thanks!


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## speedster123 (Oct 18, 2006)

The case on the Z400 is referred to as a "converable mini tower", which is basically a tall mini tower. Running 2 power supplies is do-able, but i would just buy a normal case. Why HP produced an expensive narrow case is beyond me, to save 2 inches on the width?


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## jaytechman (Sep 15, 2004)

For businesses, every inch counts. I don't understand why they made a proprietary power supply. "To save two dollars" is the consensus.

Well, my solution is actually leaving the second power supply outside the machine, on the floor behind it. That's right where the video card is anyway, at the "bottom" of the machine when it's standing on end in normal use, and I can slip two 12" "extension" PCI-Express power cables through an empty PCI slot (I'll know for sure when they arrive from NewEgg tomorrow. That will leave me a few inches of cable out the back of the machine to plug into. Should be just fine.

And Corsair's website, when beginning to create a support ticket for a power supply, shows in an FAQ for testing the power supply, which two pin positions on the 24-pin system-board plug to jump "with a paper clip" to keep the power on. Seems simple.

Thanks again!


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## jaytechman (Sep 15, 2004)

Well, it's all set up and working like a charm.

For future reference, it turns out any ATX power supply can be left external and be told to "be on" by using a paper clip to jump the green wire with a black wire next to it (closest to the center clip). That's the fourth and fifth in from the end.


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## speedster123 (Oct 18, 2006)

> For businesses, every inch counts


not when repairs are in order.
2 power supplies isnt feasable for the average user.
As far as i am concerned, HP can keep their "convertable mini tower".


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