netkas.org forum
November 16, 2018, 03:40:10 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News: Information for registering users http://forum.netkas.org/index.php/topic,2246.0.html
 
   Home   Help Search Login Register  
Pages: [1]
  Print  
Author Topic: Asus GTX 780  (Read 5424 times)
ihal9000
Newbie

Offline Offline

Posts: 4


« on: February 23, 2014, 12:18:05 PM »

Hi guys,

I'm thinking about getting the Asus GTX 780. I want to make sure that it'll work with Mac Pro 3,1. I'm not bothered by link speed or boot screen.

I noticed that there are two spare SATA ports (see screenshot attached – they are called "odd sata") on my motherboard. I'm thinking of using the 2x 6-pin ports for the 8-pin on the GTX and the two SATA ports for the 6-pin on the GTX using this adaptor http://www.amazon.co.uk/gp/product/B007Y91B80/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1.

Do you think this would be work? How much power does a SATA port give?

PCIE = 75W
2x6 pin = 150W
2xSATA = ??

Thanks for any help!
Hal


* Screen Shot 2014-02-23 at 11.13.45.png (103.26 KB, 865x634 - viewed 449 times.)
« Last Edit: February 23, 2014, 12:22:49 PM by ihal9000 » Logged
ihal9000
Newbie

Offline Offline

Posts: 4


« Reply #1 on: February 23, 2014, 12:34:37 PM »

So I just did a bit of research. SATA ports carry 15 pins, of which 9 are power. 3x3.3V, 3x5V and 3x12V with 1.5amps each pin.

A bit of maths ( http://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.htm ) we get:

3pins x 12V   = 54 W

2xPorts = 108W

Does that seem right?

Thanks!
« Last Edit: February 23, 2014, 12:39:14 PM by ihal9000 » Logged
Squishy Tia
Full Member
***
Offline Offline

Posts: 108



« Reply #2 on: February 23, 2014, 02:11:56 PM »

The ODD_SATA ports are data connections, not power connections. They will not supply power to the video card. Attempting to draw power from these ports will literally fry your motherboard. They are meant only for connecting the data cable between the drive and motherboard. Any electrical power sent through that line is minimal and serves only to function as a signal carrier.

The product you linked is for connecting to the SATA power cables that reside behind your optical drive. At most you have one free cable back there.
Logged
ihal9000
Newbie

Offline Offline

Posts: 4


« Reply #3 on: February 23, 2014, 02:24:31 PM »

Hi,

Thanks for the reply!

Do you know how much I can draw from a single SATA port? Or it worth taking the DVD drive out too?

Ta

Logged
Squishy Tia
Full Member
***
Offline Offline

Posts: 108



« Reply #4 on: February 23, 2014, 03:47:41 PM »

A single SATA port is rated for 50W of power. That is why two are needed to "create" even a single 6-pin connector and three are required for an 8-pin connector. Drawing more power than that would melt many SATA wire harnesses that are substandard in construction.

The GTX 780 requires 300w of power, and you can only achieve 225w unless you disconnect the optical drive. This is why an "external" PSU that mounts in the lower optical bay is suggested as the method of connection.
Logged
electonic
Full Member
***
Offline Offline

Posts: 114


« Reply #5 on: February 24, 2014, 06:55:03 PM »

Squishy Tia is right. But you can 2 x SATA from Hard Disk bays and Power one(1) 6 pin from them.
You can then take a 2 x 6 Pin adapter to 8 pin.
This will give you enough power for a 780. But you will lose two Hard Disk bays. Or the both ODD Bays, as far as I know.
Logged
electonic
Full Member
***
Offline Offline

Posts: 114


« Reply #6 on: February 24, 2014, 06:58:07 PM »

So I just did a bit of research. SATA ports carry 15 pins, of which 9 are power. 3x3.3V, 3x5V and 3x12V with 1.5amps each pin.

A bit of maths ( http://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.htm ) we get:

3pins x 12V   = 54 W

2xPorts = 108W

Does that seem right?

Thanks!

One SATA port can supply 4.5 Amps max. So your math is correct.
2 x SATA to 6 pin adapter = about 100 watts
2 x 6 pin to 8 pin adpater = 150 w
PCIe = 75 watts

Should work out.
Logged
ihal9000
Newbie

Offline Offline

Posts: 4


« Reply #7 on: February 24, 2014, 07:33:46 PM »

I can't get the 5.25" PSU as they don't sell them in the UK. So this solution is brilliant for me.

Thank you guys!!
Logged
Pages: [1]
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!