Confused about power consumption

[Radium_Angel]

So I have an unusual situation with a system.

It's a Dell PowerEdge T310 server I"m using as an experiment. The PCIe slot allows a max draw of 25 watts, which means anything else needs to come from an external source.

So far, so good. The challenge is I have a single SATA cord to convert to 6pin. Such an adapter exists, but according to the maths around the web, it'll give me 54 watts of extra power. Total that up, and I get 79.

So let's assume 80 watts I can pull for a video card. Not good, but some exist that fit this description.

 

To be specific, the Radeon HD 7770. Which according to here: https://en.wikipedia.org/wiki/Radeon_HD_7000_Series#Radeon_HD_7700 should be perfect. It uses 1 6pin connector and does not exceed the power requirements. Cool, so they are dirt cheap on eBay....

 

But looking around elsewhere on the web yields a number of pages whose contents state quite different numbers for power consumption.

https://www.guru3d.com/articles-pages/amd-radeon-hd-7750-and-7770-review,7.html

and

https://www.tomshardware.com/reviews/radeon-hd-7770-7750-benchmark,3135-14.html

 

So, yeah, Wikipedia is about as accurate as the local guy on the street corner, but unless I'm reading things wrong, the 7770 won't fit my needs.

Right, so you guys who are more savvy than I am on all things video card power related, feel free to chime in and enlighten me.

[Mira Yurizaki]

The specs Wikipedia lists are the ones that come from the manufacturer. The actual power consumption will vary.

 

Also PCI Express can allow for 66* watts to be delivered on the slot. While I have seen documentation from Dell for certain models saying that PCIe slots are power limited, I've also heard people using video cards that don't take PCIe power cables being used in those slots so... ¯\_(ツ)_/¯

 

*Most people will say 75W is what PCIe can provide, but the the 12V rail, which is what graphics cards care most about is about, provides 66W.

[17030644]

i can help you out

[17030644]

20 minutes ago, M.Yurizaki said:

The specs Wikipedia lists are the ones that come from the manufacturer. The actual power consumption will vary.

 

Also PCI Express can allow for 66* watts to be delivered on the slot. While I have seen documentation from Dell for certain models saying that PCIe slots are power limited, I've also heard people using video cards that don't take PCIe power cables being used in those slots so... ¯\_(ツ)_/¯

 

*Most people will say 75W is what PCIe can provide, but the the 12V rail, which is what graphics cards care most about is about, provides 66W.

but what kind of card are you talking about? because some pply say they get bottlenecks with 1050s and 1050 tis for example, as the PCIe slot is limited to 25-30W

[Mira Yurizaki]

7 minutes ago, 17030644 said:

but what kind of card are you talking about? because some pply say they get bottlenecks with 1050s and 1050 tis for example, as the PCIe slot is limited to 25-30W

No, it's not. From the PCI Express Electromechanical Specification (page 36, emphasis added):

 

Quote

A standard height x16 add-in card intended for server I/O applications must limit its power dissipation to 25 W. A standard height x16 add-in card intended for graphics applications must, at initial power-up, not exceed 25 W of power dissipation, until configured as a high power device, at which time it must not exceed 75 W of power dissipation.

 

[17030644]

41 minutes ago, Radium_Angel said:

So I have an unusual situation with a system.

It's a Dell PowerEdge T310 server I"m using as an experiment. The PCIe slot allows a max draw of 25 watts, which means anything else needs to come from an external source.

So far, so good. The challenge is I have a single SATA cord to convert to 6pin. Such an adapter exists, but according to the maths around the web, it'll give me 54 watts of extra power. Total that up, and I get 79.

So let's assume 80 watts I can pull for a video card. Not good, but some exist that fit this description.

 

To be specific, the Radeon HD 7770. Which according to here: https://en.wikipedia.org/wiki/Radeon_HD_7000_Series#Radeon_HD_7700 should be perfect. It uses 1 6pin connector and does not exceed the power requirements. Cool, so they are dirt cheap on eBay....

 

But looking around elsewhere on the web yields a number of pages whose contents state quite different numbers for power consumption.

https://www.guru3d.com/articles-pages/amd-radeon-hd-7750-and-7770-review,7.html

and

https://www.tomshardware.com/reviews/radeon-hd-7770-7750-benchmark,3135-14.html

 

So, yeah, Wikipedia is about as accurate as the local guy on the street corner, but unless I'm reading things wrong, the 7770 won't fit my needs.

Right, so you guys who are more savvy than I am on all things video card power related, feel free to chime in and enlighten me.

I recommend you to ask this question in POWER SUPPLIES

 

you can find better answers there.

 

my answer is:

 

1.- SATA to PCIe? that sounds like asking for trouble, if your PSU doesn't even have a 6 pin then it musn't be a good one so it's a risk.

 

2.- wikipedia shows TDP and TDP isn't equal to power draw. VGA power consumption veries per model, so not all 7770s have the same power draw.

 

3.- You also need to consider that not all websites measure GPU draw  the same way so that certainly affects the results. For example guru3D doesn't take power efficiency loss into account, so I prefer tomshardware or techpowerup for power consumption figures as they have very sophisticated equipment.

 

4.-  If you don't now what to buy, just reduce the power limit on msi afterburner once you buy the card.

[Radium_Angel]

26 minutes ago, M.Yurizaki said:

The specs Wikipedia lists are the ones that come from the manufacturer. The actual power consumption will vary.

 

Also PCI Express can allow for 66* watts to be delivered on the slot. While I have seen documentation from Dell for certain models saying that PCIe slots are power limited, I've also heard people using video cards that don't take PCIe power cables being used in those slots so... ¯\_(ツ)_/¯

 

*Most people will say 75W is what PCIe can provide, but the the 12V rail, which is what graphics cards care most about is about, provides 66W.

Can you point to those posts about going over that?

I have a PowerEdge 2900 Model III that I successfully installed a GTX 660 in, feeding off excess power, because it has a bunch to spare, but the T310 is a lower order server build and I'd rather not fry it (or start a fire) by simply plugging in a video card and seeing what happens...

[Radium_Angel]

2 minutes ago, 17030644 said:

4.-  If you don't now what to buy, just reduce the power limit on msi afterburner once you buy the card.

Does that program exist under Linux? Because this is a Linux box...

 

1.- SATA to PCIe? that sounds like asking for trouble, if your PSU doesn't even have a 6 pin then it musn't be a good one so it's a risk.

 

It's a server system, not a gaming box, but I"d like to push it past the design spec, as I have had with the PE 2900. So it makes sense the PS doesn't have a 6pin cable.

[17030644]

Just now, Radium_Angel said:

Does that program exist under Linux? Because this is a Linux box...

to be honest with you, I don't know

 

but in gereral look for overclocking suites and reduce the power limit

 

 

[Mira Yurizaki]

1 minute ago, Radium_Angel said:

Can you point to those posts about going over that?

I have a PowerEdge 2900 Model III that I successfully installed a GTX 660 in, feeding off excess power, because it has a bunch to spare, but the T310 is a lower order server build and I'd rather not fry it (or start a fire) by simply plugging in a video card and seeing what happens...

I basically looked up something like using a GTX 750 Ti or some other known video card that doesn't use a PCIe auxiliary power cable on the Dell model in question (It was an Optiplex 7xxxx model or something)

[Radium_Angel]

5 minutes ago, M.Yurizaki said:

It was an Optiplex 7xxxx model or something

I'll look around but the T310 is a server rig, not a home-use system and they have radically different design specs. I'll see what I can find.

[Mira Yurizaki]

3 minutes ago, Radium_Angel said:

I'll look around but the T310 is a server rig, not a home-use system and they have radically different design specs. I'll see what I can find.

The Optiplex is an office computer, so it's given the same treatment as any other business oriented computer Dell has.

[Mira Yurizaki]

If you need some evidence that video cards of that power dissipation are fine: https://www.userbenchmark.com/System/Dell-PowerEdge-T310/5938