Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

980Ti, internal power?

AkuskaUK

AkuskaUK

macrumors 6502
Original poster
Mar 18, 2011
376
177
Shanklin, Isle Of Wight
Hi everyone,

I recently purchased a 980Ti to replace my ageing 770, on MVC's website they say that their flashed versions are able to ran on internal power. I rang MacStoreUK (MVC's Europe supplier) and they said that it should be ok once flashed too.

The questions I have are:
  1. How will the card be fully powered if there is an 8 pin connection when the Mac Pro have 2x6?
  2. Will a 6 pin be ok in there or will I have to get a 6 to 8 converter?
  3. Will that be safe using said converter?
  4. Is there a better way to power the card that I don't have to run an external PSU?
  5. Would I be able to use the optical drive Sata connection for more power?
  6. Will I have to remove any drives so that I'm not overloading the PSU?
If these questions have already been answered, I apologise.
Thanks in advance!
 
AkuskaUK said:
Hi everyone,

I recently purchased a 980Ti to replace my ageing 770, on MVC's website they say that their flashed versions are able to ran on internal power. I rang MacStoreUK (MVC's Europe supplier) and they said that it should be ok once flashed too.

The questions I have are:
  1. How will the card be fully powered if there is an 8 pin connection when the Mac Pro have 2x6?
  2. Will a 6 pin be ok in there or will I have to get a 6 to 8 converter?
  3. Will that be safe using said converter?
  4. Is there a better way to power the card that I don't have to run an external PSU?
  5. Would I be able to use the optical drive Sata connection for more power?
  6. Will I have to remove any drives so that I'm not overloading the PSU?
If these questions have already been answered, I apologise.
Thanks in advance!
Click to expand...

1. With a 6 to 8 pin and a 6 to 6 pin cable. Already included with the card when buying from MVC.
3. Yes
4. No need for an external PSU at all if you don't overclock the card
 
Hi,

I've this version eVGA 06G-P4-4995-KR (from amazon) which has one 8 and 6pins.
I'm powering the card using the 2x6pin to 8pin of the card and the other I get the additional 6pin from the optical bay where I have also a SSD.
Everything seems to work like a charm without issue on macOS and Window.
 
Synchro3 said:
1. With a 6 to 8 pin and a 6 to 6 pin cable. Already included with the card when buying from MVC.
3. Yes
4. No need for an external PSU at all if you don't overclock the card
Click to expand...

Won't the 6-8 draw too much power from the logic board?

superparati said:
Hi,

I've this version eVGA 06G-P4-4995-KR (from amazon) which has one 8 and 6pins.
I'm powering the card using the 2x6pin to 8pin of the card and the other I get the additional 6pin from the optical bay where I have also a SSD.
Everything seems to work like a charm without issue on macOS and Window.
Click to expand...

What cable did you use to get the power from the optical drive bay?

Thanks for the replies though, I know these questions can get annoying but I just don't want to damage the Mac Pro as its essential to my university work.
 
Menel said:
http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-980-ti/specifications
980TI is a 250W card... only jeez. That's seriously heavy.

ok well a GTX 770 is already 230W. The 20W difference probably isn't significant.

Don't sweat the difference in 6pin vs 8pin connectors.
Click to expand...

So I should be ok using a 6 to 8 pin connector?

pastrychef said:
250W is more than 10% above 225W. Overclocked versions will obviously draw even more than 250W.
Click to expand...

Mines the normal version, not overclocked. Will it be too much? How can MVC say that it can be powered internally if it draws so high?
 
Hi AkuskaUK, here is the cable I ordered on the top of the card:

2x data power to 6pin PCIe. here
PCIe 6 pin extension cable 45mm. here
Dual 6-pin PCIe to 8-pin power cable included within the pack. like that one
2x min 6-Pin PCIe to PCIe here
 
Last edited:
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
Synchro3 said:
No, the board supports much more than 75 Watt. Read this: https://forums.macrumors.com/thread...ible-with-older-macpro.1987000/#post-23224762

And I'm using GTX Titan X without issues since more than one month.
Click to expand...

Everything is fine with no power downs? Have you ever had problems with it?

superparati said:
Hi AkuskaUK, here is the cable I ordered on the top of the card:

2x data power to 6pin PCIe. here
PCIe 6 pin extension cable 45mm. here
Dual 6-pin PCIe to 8-pin power cable included within the pack.
Click to expand...

Thank you, ill take a look :)
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
AkuskaUK said:
Mines the normal version, not overclocked. Will it be too much? How can MVC say that it can be powered internally if it draws so high?
Click to expand...

Using a card rated at 250W will undoubtedly be pushing the power connectors beyond spec. Whether or not it's safe and/or acceptable is up to you (the consumer) to decide.

There are quite a few users who use 250W rated video cards without issues. YMMV.
 
AkuskaUK said:
Everything is fine with no power downs? Have you ever had problems with it?
Click to expand...

No problems, in Windows playing GTA V with high settings (no long shadows) and Starcraft 2 @ 4K without issues.

In OS X El Capitan with latest drivers sometimes rarely fragments in videos, but this is a software issue.

In macOS Sierra OpenCL issues solved.

But never a Shutdown.
 
Last edited:
  • Like
Reactions: mokeiko
Synchro3 said:
No problems, in Windows playing GTA V with high settings(no long shadows) and Starcraft 2 @ 4K without issues.

In OS X El Capitan with latest drivers sometimes rarely fragments in videos, but this is a software issue.

In OS X El Capitan OpenCL issues solved.

But never a Shutdown.
Click to expand...

Great to hear! Are you using a 6-8 pin adapter?
 
AkuskaUK said:
Will that be safe using said converter?
Click to expand...

I've did some tests about power draw by using 2x 7950. That can easily draw more than a single 980Ti. And here is the result.

https://forums.macrumors.com/thread...or-approaching-silence.1982499/#post-23120938

The cMP can practically deliver up to about 120W from each mini 6pin. However, I must say that officially NOT safe to do so. It works, I used this dual 7950 for more than a year already. As you can see from the test, even running Furmark on both 7950 at the same time, the cMP still survive. However, it's all up to you if you are happy to go beyond the official 75W limit. Once you go beyond that, nothing is safe technically.
 
  • Like
Reactions: Synchro3
h9826790 said:
I've did some tests about power draw by using 2x 7950. That can easily draw more than a single 980Ti. And here is the result.

https://forums.macrumors.com/thread...or-approaching-silence.1982499/#post-23120938

The cMP can practically deliver up to about 120W from each mini 6pin. However, I must say that officially NOT safe to do so. It works, I used this dual 7950 for more than a year already. As you can see from the test, even running Furmark on both 7950 at the same time, the cMP still survive. However, it's all up to you if you are happy to go beyond the official 75W limit. Once you go beyond that, nothing is safe technically.
Click to expand...

Thank you, ill have a read of that!
 
If you have a fully loaded tower like mine, you most certainly do need an external PSU for the 980ti. I have 6 internal drives, full RAM and 4 PCI cards. My tower would run for a few minutes then crash. External PSU fixed that.
 
JesterJJZ said:
If you have a fully loaded tower like mine, you most certainly do need an external PSU for the 980ti. I have 6 internal drives, full RAM and 4 PCI cards. My tower would run for a few minutes then crash. External PSU fixed that.
Click to expand...

It's a simple supply vs demand calculation. The 980W PSU should be able to handle a fully loaded cMP.

e.g.
Logic board 80W
CPU 130W x2 = 260W
RAM 3W x8 = 24W
980Ti 250W
HDD 10W x6 = 60W (SSD will use much less)
Super Drive 30W
Fan 2W x5 = 10W
PCIe USB 3.0 40W (all 4 port able to deliver 2A charge)

All the above estimation is actual already on the safe side, and if stress everything together at the same time, it's about 750W, which still below the 980W rated PSU's limit. Unless you install another 980Ti (or another very power hungry PCIe card), the PSU should be fine.
 
Last edited:
JesterJJZ said:
If you have a fully loaded tower like mine, you most certainly do need an external PSU for the 980ti. I have 6 internal drives, full RAM and 4 PCI cards. My tower would run for a few minutes then crash. External PSU fixed that.
Click to expand...

I have 4 internal drives, but thinking about dropping that to 2/3. I have full ram slots, but only 32gb.

h9826790 said:
It's a simple supply vs demand calculation. The 980W PSU should be able to handle a fully loaded cMP.

e.g.
Logic board 80W
CPU 130W x2 = 260W
RAM 3W x8 = 24W
980Ti 250W
HDD 10W x6 = 60W (SSD will use much less)
Super Drive 30W
Fan 2W x5 = 10W
PCIe USB 3.0 40W (all 4 port able to deliver 2A charge)

All the above estimation is actual already on the safe side, and if stress everything together at the same time, it's about 750W, which still below the 980W rated PSU's limit. Unless you install another 980Ti (or another very power hungry PCIe card), the PSU should be fine.
Click to expand...

Thanks for this!

Synchro3 said:
Yes, one 6 to 8 pin cable and one 6 to 6 pin cable.
Click to expand...
Thank you!
 
AkuskaUK said:
Mines the normal version, not overclocked. Will it be too much? How can MVC say that it can be powered internally if it draws so high?
Click to expand...
TDP is a rough design spec, not an exact measurement of power. In practice, a stock 980 Ti will draw much less than 250 watts. There are other 250 watt cards that won't work in a Mac Pro. Similarly, the 75 watts for each 6 pin power is the design rating, and in practice they can actually deliver more. The combination of those two margins means that a stock 980 Ti can safely be run off of 6-8 pin power in a Mac Pro. Many people are not comfortable deliberately biting into the design margins of the power supply and prefer to make other arrangements for power. I'm comfortable using my 980 Ti on a 6-8 pin cable, but I quite understand the caution of others.
 
Shamgar said:
TDP is a rough design spec, not an exact measurement of power. In practice, a stock 980 Ti will draw much less than 250 watts. There are other 250 watt cards that won't work in a Mac Pro. Similarly, the 75 watts for each 6 pin power is the design rating, and in practice they can actually deliver more. The combination of those two margins means that a stock 980 Ti can safely be run off of 6-8 pin power in a Mac Pro. Many people are not comfortable deliberately biting into the design margins of the power supply and prefer to make other arrangements for power. I'm comfortable using my 980 Ti on a 6-8 pin cable, but I quite understand the caution of others.
Click to expand...

Thank you for explaining it :) I think I'm just going to go with a 6-8 pin adapter and run it from internal power :D
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back