2 x gtx 780 ti in HP z800 - power supply

[andywillers]

Hi I am trying to install 2 graphics cards in my z800 which has 2 6 pin power outputs, but both cards have 2 8 pin power inputs. My PSU is 1100w.

What cables do I need to make this work? Sorry for my lack of technical knowledge, this is my first real foray into PC innards...

 

[bicycle_repair_man]

If your PSU doesn't have sufficient PCIe connectors, then you're out of luck I'm afraid.

 

[Bafioo]

If your PSU doesn't have sufficient PCIe connectors, then you're out of luck I'm afraid.

That's actually not right, there are adapters.

Like this one:

http://www.systemagnostic.com/wp-uploads/2013/01/molex_pci-e.jpg

They usually send you this togheter with the GPU, inside the box, i mean.

And in case you don't have one, there is an amazon link:
http://www.amazon.com/HDE-PCI-Express-Pin-Molex/dp/B0041P73LE/ref=sr_1_2?ie=UTF8&qid=1423830481&sr=8-2&keywords=2x+Molex+4+Pin+%3E+PCIe+6+Pin

 

[andywillers]

If your PSU doesn't have sufficient PCIe connectors, then you're out of luck I'm afraid.

That's actually not right, there are adapters.

Like this one:

http://www.systemagnostic.com/wp-uploads/2013/01/molex_pci-e.jpg

They usually send you this togheter with the GPU, inside the box, i mean.

And in case you don't have one, there is an amazon link:
http://www.amazon.com/HDE-PCI-Express-Pin-Molex/dp/B0041P73LE/ref=sr_1_2?ie=UTF8&qid=1423830481&sr=8-2&keywords=2x+Molex+4+Pin+%3E+PCIe+6+Pin

Great! So it is doable - my PSU definitely is rated high enough to handle the two cards. Thanks for the link.

Should I run into any troubles?

Cheers!

 

[Bafioo]

If your PSU doesn't have sufficient PCIe connectors, then you're out of luck I'm afraid.

That's actually not right, there are adapters.

Like this one:

http://www.systemagnostic.com/wp-uploads/2013/01/molex_pci-e.jpg

They usually send you this togheter with the GPU, inside the box, i mean.

And in case you don't have one, there is an amazon link:
http://www.amazon.com/HDE-PCI-Express-Pin-Molex/dp/B0041P73LE/ref=sr_1_2?ie=UTF8&qid=1423830481&sr=8-2&keywords=2x+Molex+4+Pin+%3E+PCIe+6+Pin

Great! So it is doable - my PSU definitely is rated high enough to handle the two cards. Thanks for the link.

Should I run into any troubles?

Cheers!

Any at all! Those cables are made for that and yes your power supply is enough for a 780 sli, even 800W are enough, as long as they are good quality ones.

Tho even if your 1100W was low quality it has to warrantly an ammount of Wattage, check the side of the PSU and read how much wattage does it warrant to you.

Keep in mind two 780 Ti pushed to the maximum will be consuming 617W.
So considering the other components even 750W are enough, not if you have and AMD CPU FX 9000+

But i still think your PSU warrant atleast 950W if not more. Check the side of your PSU and you'll be fine

 

[andywillers]

If your PSU doesn't have sufficient PCIe connectors, then you're out of luck I'm afraid.

That's actually not right, there are adapters.

Like this one:

http://www.systemagnostic.com/wp-uploads/2013/01/molex_pci-e.jpg

They usually send you this togheter with the GPU, inside the box, i mean.

And in case you don't have one, there is an amazon link:
http://www.amazon.com/HDE-PCI-Express-Pin-Molex/dp/B0041P73LE/ref=sr_1_2?ie=UTF8&qid=1423830481&sr=8-2&keywords=2x+Molex+4+Pin+%3E+PCIe+6+Pin

Great! So it is doable - my PSU definitely is rated high enough to handle the two cards. Thanks for the link.

Should I run into any troubles?

Cheers!

Any at all! Those cables are made for that and yes your power supply is enough for a 780 sli, even 800W are enough, as long as they are good quality ones.

Tho even if your 1100W was low quality it has to warrantly an ammount of Wattage, check the side of the PSU and read how much wattage does it warrant to you.

Keep in mind two 780 Ti pushed to the maximum will be consuming 617W.
So considering the other components even 750W are enough, not if you have and AMD CPU FX 9000+

But i still think your PSU warrant atleast 950W if not more. Check the side of your PSU and you'll be fine

Hey there again - so I've been poking round inside my computer again and there don't seem to be enough molex connectors to power both cards. What there are is 2 free 6 pin PCIe ports - would something like this work? http://www.amazon.co.uk/DeLOCK-cable-Power-PCIe-pin/dp/B00FOQW2GA/ref=sr_1_2?s=computers&ie=UTF8&qid=1424075706&sr=1-2&keywords=pcie+6+pin+to+2+x+8+pin

One port for each card...

 

[Voz]

did you ever get this working?

 

[andywillers]

did you ever get this working?

Nope It looks like the power supply is powerful enough but I was too scared to try and run both cards off the limited power ports. Let me know if you fidure out a work around cause I'd love to get the second card in...

 

[Voz]

really? i don't think there is anything bad that can happen. As far as i understand, worst case, computer just shuts down if there isn't enough power.

according to google anyway.. http://www.tomshardware.co.uk/answers/id-2298097/power-supply-watts.html

and im pretty sure, the HP systems have high quality psu's in them.

 

[RobCrezz]

Is this for gaming? As the motherboard will need to support SLI if you want to game using both cards.

Check the PSUs 12v amperage to get an idea of its real power. On amazon you can get pci-e 6 pin to 8 pin adaptors also.

 

[andywillers]

really? i don't think there is anything bad that can happen. As far as i understand, worst case, computer just shuts down if there isn't enough power.

according to google anyway.. http://www.tomshardware.co.uk/answers/id-2298097/power-supply-watts.html

and im pretty sure, the HP systems have high quality psu's in them.

It's more that there aren't enough 8 pin connectors for the 2 cards - each of the GPUs take 2 x 8 pin connectors and there are only 2 x 6 pin connectors in the case - I don't think you can run so much power off two connectors. I may be wrong though I'm no expert!

 

[RobCrezz]

really? i don't think there is anything bad that can happen. As far as i understand, worst case, computer just shuts down if there isn't enough power.

according to google anyway.. http://www.tomshardware.co.uk/answers/id-2298097/power-supply-watts.html

and im pretty sure, the HP systems have high quality psu's in them.

It's more that there aren't enough 8 pin connectors for the 2 cards - each of the GPUs take 2 x 8 pin connectors and there are only 2 x 6 pin connectors in the case - I don't think you can run so much power off two connectors. I may be wrong though I'm no expert!

Yeah you can, the connectors and the wireing will take the amperage.

As long as the PSU is rated as high as the op says it is on the 12v rail, then splitter adaptors should be fine.

 

[ImpartialTech]

In our OEM Workstations we have used Dedicated Graphics Power Supplies, like the VisionTek Juicebox. It fits into a vacant 5.25" bay.
Problem is the Hp z800 isn't certified for Geforce sli, only Quadro sli. You can still use the HyperSli workaround to get Geforce sli working.

 

[andywillers]

In our OEM Workstations we have used Dedicated Graphics Power Supplies, like the VisionTek Juicebox. It fits into a vacant 5.25" bay.
Problem is the Hp z800 isn't certified for Geforce sli, only Quadro sli. You can still use the HyperSli workaround to get Geforce sli working.

This is music to my ears... I don't need SLI as I'm using the cards for rendering and not gaming. Does the additional power supply switch on / off with the computer? Is it a complicated install? Thanks!

 

[ImpartialTech]

There are several different brands. Thermaltake made 450w and 650w models. ePower made one. A VisionTek juicebox has been in one of my Hp XW series workstations for 6 years with no issue.
They fit into ether 1x 5.25" bay or 2x5.25" bays (450w and 650w respectively). You connect one molex from your primary psu into the Juicebox, allowing it to turn on and off via the regular power button on your computer.
The real problem you will run into is how rare these seem to be these days. Not sure why, but it seems most companies discontinued these power supplies, despite fantastic reviews. Most folk have never heard of them.
Just Google "Dedicated VGA Powersupply". You'll find them. I can't post a link here, but I can see several on ebay right now.