My ps & Dual gtx 570's

[karmar52]

Hi all.

I'm new here & have a question concerning my ps. What i have is an XPS 730 with a core 2 quad extreme qx 9650 & dual 9800 gt nvidia cards all on a 1000 watt ps. I want to upgrade to dual 570's but not sure if my ps can handle it. the label on it says,

12vA - 18 amps
12vB - 18 amps
12vC - 18 amps
12vD - 18 amps
12vE - 18 amps

and my question is are these all on a what is called single or multi rails & do you think it will be enough. it has 4 - 6 pin connectors for graphics cards. Also how do i know what 6 pin connector comes off which.

[Stefan Payne]

1. Don't know without the rail distribution...
Try the color of the +12V wires. With a multi rail unit they are normally not just yellow...

2. Single rail or multi rail is equivalent to having a breaker box or not having one...
So if one cable pulls more than the desired amperage, it will burn on a single rail unit as there is nothing to stop it from using the whole power of the unit...

[Tator Tot]

Each set of PCIe connectors is on it's own Rail (C & D.)

So it will work.

Rail distribution is:
A = Motherboard, 10pin, & 3 x Molex + 1 x Mini Molex (Floppy)
B = 2 x CPU
C = 2 x PCIe
D = 2 x PCIe
E = 6 x SATA

EDIT: For anyone wondering, 10 pin just powers fans & LED's while the Molex connectors are usually hooked up to ODDs.

[siana]

There are 5 (specified) rails. The only reasonable choice i see is that CPU is on one rail, and then each GPU 6-pin connector in its own rail. This still leaves the question open, which rail is connected to Mainboard-side of PCI-e, and which rails go into disk connectors and the like. Maybe describing each of the cables which come out of the PSU will help make it more specific.

EDIT: WHOOPS disregard this, Tator has the leading!

Here Wikipedia mentions a unit closely related to yours: http://en.wikipedia.org/wiki/Dell_XP...Unit_.28PSU.29
The advice to combine multiple Molex plugs into GPU power is a very, very bad idea, don't do this. Given that you have a choice to combine 6+6pin into 8pin with an adapter, this is a much better idea and unless your PSU is overspecified by a major factor (unlikely i would say), it should work perfectly.

As a word of note, you may notice that single-thread performance of your CPU and performance of mainboard chipset may start becoming a limiting factor in the performance of your system, but this will depend on specific software that you want to use - pure benchmarks are likely to be affected less than real software. An upgrade to a single high end single-chip GPU (570, 580, maybe even 670, 680) may be worth it both financially and performance wise, while if you chose to upgrade to two 570, you may find that disabling the second GPU will yuild higher performance with some software which has particularly high draw call count per frame.

[karmar52]

I just want to thank all of you for the time you took to find info regarding my question & feel that i will go ahead with my purchase of the 570's. I just got thru installing win 7 ultimate & upgraded my mem0ory from 4 to 8 gb so i'm hoping to see a significant performance boost.

thanks again

[karmar52]

I do have a few more question if it is ok. I looked thru my owners manual & found that p3 & p4 are for gpu's & p13 & p14 are for gpu's all of which are 6 pin conn. If the label on my ps states that 12v A thru 12v E are all 18 amps does it mean that p3 & p4 put out 18 Amps total or 36 Amps combined. Also p13 & p14 the same. Or is the combined amps for each pair of pcie conn. a total of only 18 amps. there is no way to really tell right ?

[Tator Tot]

Each set (P3 & P4, as well as P13 & P14) are on a rail.

So rail 1 = connectors P3 & P4
Rail 2 = connectors P13 & P14

The OCP set point for those rails is 18A, which means that your current limit is 18A (or 18A x 12V = 216w)