Z820 PSU Question

[PatBranch]

I have a z820 that I'm going to add an EVGA 1080 Ti GPU to. It has the 1125 Watt PSU and I'm wondering if I need the 1275 W PSU. I found this cable to convert the 6 pin cable to an 8 pin for it. https://www.amazon.com/HP-Power-Supply-Adapter-N1G35AA/dp/B011Z74OGW

It was also have a 7200 rpm hard drive, 2 sata SSDs and 1 nvme SSD. 1125 W should be enough right?

[SDH · Accepted solution]

Pat..... that is the right choice.  This is exactly what HP engineered those adapters for.

 The thing to know is that the HP PCIe supplemental power cables coming from the HP power supplies provide much more wattage than a "ATX-standard" cable.  The ATX standard cable is 75W max.  The HP cable is rated for its amperage times voltate (18A x 12V = 216 Watts).  The amperage for each HP PCIe supplemental power supply is listed on the HP power supply label (usually has a G1/G2/G3 in its code).  For years each of these HP cables has been rated for up to18A.

There are some very cheaply made 6-pin to 8-pin adapters out in the market.  Some have only a fraction of their sockets populated with wires.  Some have tiny wires rather than HP-spec thicker wires.  At 25-30 bucks I'd always go with the HP adapter and know that my video card could pull a full 216W through that adapter.  Please also note that the card slot itself provides 75W up to the card.  Thus, your card will be getting access to a full 291W to play with from the slot plus the cable, but only if you have a properly engineered adapter.  I'm not saying only the HP adapter can pull this off, but I am saying that many others can not (and how do you know the good from the bad?).

You have more than enough capability via your current power supply.... big old hard drives used much more power than your SSDs, so that is in your favor also.  I think you'll be able to run a mini-fridge off it also.

[PatBranch]

Awesome, thank you so much for all the details! I look forward to having a proper workstation for editing.

I hadn't ever heard of a PCI slot providing power. That's wild. I'm surprised a gaming card would support that.

[PatBranch]

I'll have to add a mini fridge or kegerator into the mix! h

[Scoobis]

the 1125w ps is rated at 1275w at us line voltage. 115v-127v ac

if you're in Japan, at 100vac then it is rated at 1125W

you don't "need" an adapter...let me explain...

the first 6 pins of your 8 pin block on your graphics card match with the 6 pins on the power cable.  this is a design intent of the 8pin connector, that you an plug a 6pin power connector into it  its actually 6+2 the additional 2 is an additional sense wire and an additional ground wire..  each of the connectors are already rated for 18A each, so with 2 connected its capable of 36A or 432W.  if you look at the photo below it shows on the 6 pin connector that pin to is not occupied in the 6 in spec, however, almost universally power connectors have 12v on this line on the 8 ppin connectors.

using an adapter instead of just plunging it into the first 6 pins of your 8 pin jack directly is not going to increase the maximum power available to the card. in fact, it could provide a failure point if the wires are to thin on the adapter, or, the adapter was poorly assembled

You can use a 6pin to 8pin adapter if it makes you feel better ..  but be very careful where you source it, some have very thin wires.