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Why no 2X ATI Radeon HD 5870 on BTO page?
- Thread starter sparkie7
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DigitalVT
macrumors regular
Well I ordered mine with one 5770 with the idea of adding a 5870 later when they become available, surely there will be enough power for this!!!
peskaa
macrumors 68020
There are two feeds off the board in total. The 5770 uses one, so you can have two cards. The 5870 uses two, so you can only have that single card installed.
The way round it, of course, is to install a 5870 and then have a GT120 (or several) for extra screens, as they don't need power feeds and OS X copes fine with a mix and match of GPU vendors.
For running three 30"ers, yes, the pair of 5770s. You can't Crossfire the boards, but you'll get better performance on a whole.
The way round it, of course, is to install a 5870 and then have a GT120 (or several) for extra screens, as they don't need power feeds and OS X copes fine with a mix and match of GPU vendors.
For running three 30"ers, yes, the pair of 5770s. You can't Crossfire the boards, but you'll get better performance on a whole.
DigitalVT
macrumors regular
I was thinking of getting maybe a third power feed off of the unused (2nd) CD/DVD tray??
Cindori
macrumors 68040
The best way to safely run a second 5870 (or 5770 + 5870, or even 2x 5770's + 1x 5780), is to run a separate power supply.
The easiest way to do this, is by using a graphics card PSU that's meant to fit in a 5.25" bay (here). Cheap too. If the second optical bay is used, then run it externally (not pretty, but better than a PC PSU due to the mess of unused wiring, and no need to jump the green and black wires to make it work).
As per the idea of pulling the power from the backplane connector located at the empty optical drive (power + data), I wouldn't recommend it. It's not likely to be able to provide sufficient current, and could actually damage the system.
Nor would trying PSIG Y splitters (again, too much current on the rail, and in this instance, melt the solder for the traces on the backplane board = short circuit, resulting in a new backplane board needed; board that has the PCIe slots on it).
The easiest way to do this, is by using a graphics card PSU that's meant to fit in a 5.25" bay (here). Cheap too. If the second optical bay is used, then run it externally (not pretty, but better than a PC PSU due to the mess of unused wiring, and no need to jump the green and black wires to make it work).
As per the idea of pulling the power from the backplane connector located at the empty optical drive (power + data), I wouldn't recommend it. It's not likely to be able to provide sufficient current, and could actually damage the system.
Nor would trying PSIG Y splitters (again, too much current on the rail, and in this instance, melt the solder for the traces on the backplane board = short circuit, resulting in a new backplane board needed; board that has the PCIe slots on it).
Seems like a waste of time, money and energy when the Mac Pro has a 1200W PSU available.
I'm sure you could make or find some adapters that can draw the power off the SATA connectors... 😛
Edit: Assuming the SATA connectors have a decent enough power rating.
If your really brave then opening up the PSU to take another feed off there would be a way forward 😛 Although warranty issues!
peskaa
macrumors 68020
And the cabling for such would be a nightmare. Finding space for optical drive into PCIe bay leads is hard enough...
Cindori
macrumors 68040
barefeats
macrumors 65816
Brilliant. In the past, I used an external modified ATX 500W power supply to drive dual GPUs that required two power feeds each. It was not a pretty sight with the side cover off and power cables running from the ATX to the PCIe bay.
The Optical Bay PSU is a more elegant solution if you want to run dual 5780s. If you are running Windows via Boot Camp, you should be able to jumper them with a CrossFire connector (assuming that connector isn't covered up).
That way you'd block the first hard drive and you wouldn't be able to slide in the optical bay any more.
There is however allocated space around the upper left corner of the logic board. The optical bay SATA cables also run through there and there is more space for additional cabling.
All it takes is to disassemble the front PCIe fan and the supply cable cover behind the optical bay.
There is, however, no way to force two 6 pin connectors through there. Taking of the connectors should work though.
Cindori
macrumors 68040
😛
Unfortunately I can't see anything on that pic. I just made a quick one.
As you can see the '09 and thus the '10 models don't have any holes in the bottom plate. You can however access the ODD bay through the space on the left.
All you have to do is remove the power supply cable cover and the front PCIe fan.
Spanky Deluxe
macrumors 603
You can buy six pin pcie power cable y-solitudes to power two 5870s. Of course, you'd be running more power through the tracers on the board than they were specified for. I remember people having some stability problems powering a second card from the optical bay but I ran two 4870s in this manner in my Mac Pro for about seven months without issue before upgrading.
It's to do with how the +12V rails are used.
There's no actual statement of the PSU size in the specification page, just voltage and current consumption (which are peak values BTW). But even if it actually is a 1200W unit, that's likely a peak rating, not a continuous one. So take that number and divide by SQRT 2 (1200W/1.414) = 850W. If it's the same as previous models (980W), then the continuous power rating would = 980W/1.414 = 700W.
Yes, there are adapters out there (indirectly, so multiples would be required; and possibly modified for gender).
They don't. Worst case, it's meant to handle ~40W (peak power draw of a mechanical drive during spin up).
You'd need to know what rail goes where, what the current load is on each, and what they're rated for in order to determine you can draw sufficient power. You can't just tie them together either, as the voltage regs usually are not using matched components (transistors for example) = uneven power draw that will burn one, then the other out.
I recall one person for sure that tried this, and burnt out their board. 😱 The solder on the traces melted, causing a short that in turn, burnt it out. 🙁
Not good IMO.
Justinf79
macrumors 6502
So can OS X use both the GT120 and 5870 together in OpenCL stuff?
Also, how will Win7 handle this setup? I ask because I have a GT120 atm, and thinking about getting the 5870 when it's available.
gt120 doesn't do openCL
and windoze hates cards from different vendors being present, although you should just be able to disable the gt 120 in the devices control panel.
how would one power that 5.25" bay PSU without leaving the case open? i'm really interested in this, but i don't wanna have my case open cause kitty loves to rub up on my computer when i don't pay attention to her...
Justinf79
macrumors 6502
Uh, no, the GT 120 most certainly DOES do OpenCL. I've used OpenCL on my GT 120.
http://www.nvidia.com/object/io_1252000156987.html
There's no 2x 5870 option because doing so would set your Mac Pro on fire...
On a related note, just how much heat do they generate? 😛
On a related note, just how much heat do they generate? 😛
Also, I should mention that VISTA hated cards from different vendors, that was fixed in Windows 7.