Hi guys,
 
Lately I have started to experience some weird behaviour on my gaming rig. First I guess I should mention the essentials in my rig. I am running the x58 Sli mobo (the first version released) and 2x NVidia GTX 480 cards in SLi. I am running it on a Corsair HX 1000W, so I should be fine "power wise".
 
The weird thing that has started to happen is that I lose one of the graphics card, thus also losing SLi in the NVidia driver panel after a restart of the computer. The gfx card is coming back again if I do a cold boot. But as soon as I do a warm boot, it disappears again.
 
Both cards are fine if I run only one of them.
 
Anyone out there that can point my in the right direction how to fix this or what this symptom might be?
 
 
 

I resolved my issues with an upgrade to the AX1200. the single rail solution was a god send, I no longer had to worry about deviding railes.

Hi KMoore,
 
Should single rail / multi rail have an impact on this at all? I thought that was only affecting when the PSU would turn itself off as a result of something bad. So with single rail you stand a chance of frying your computer as opposed to multi rail.
 
I am not sure the PSU is the problem on my rig, and dishing out that much money on a new PSU like that when I already have the 1000W feel like a waste. Then I should rather return the PSU and get a new if it was the PSU that was the problem, cause it should be able to cope fine with my specs.
 
Any other suggestions guys? Could it be something with the mobo itself?
 
I forgot to mention that whenever I reset the CMOS it will also always show up again too.
 
I have also tried a different SLi bridge.

The rail issue comes into play when you have rails incapable of meeting demand Example I had a HX1000 Corsair PSU, technicaly it's two 500w PSU's in the same case, Running a pair of 580's they spec at Per nvidia min PSU 600W with a max card draw of 244W ; Now that is only about 850 watts, so a 1000 wat PSU should be more than enough But because of the devided rail at 500 watts One rail will be short by 100 watts and the other have about 250 watts to spair, Technicaly you could take half the power from each rail, for each card, but the PSU manual says NOT TO. Un overclocked your processor is going to pull 130 watts alone. when I changed to the AX1200, it had a single rail, so I no longer had an issue, and could run three if I wished. see diagram below for HX1000 Now something else you may be able to try, Order the powerboost from acceseries for about $10, and place it on the rail that only has one card, and connect that to an unused PCI-e slot.
 

The newer HX1050 from Corsair only has a single rail and will not have this problem

Lovely stuff KMoore. 
 
So much conflicting information out here on the interwebz. There was one long article I once read about multi / single rail where the author basically said that it didn't impact the power you got at all, and only would impact when the PSU shut itself down completely to protect the system. Or maybe I misunderstood. 
 
I will look at the powerboost option more closely and report back here if there is any news. Thanks again guys.
 
PS: Oh yeah, I found the post over at Overclockers.net. The thread is called "Single Rail vs. Multi Rail *Explained*" (I can't post URL's just yet.)

The Corsair HX 1000 is prone to failure.  It sounds like it may be doing that.  The good news is that Corsair will RMA it with a brand new HX 1050.  That is what I would do.  RMA the PSU.

Hi guys,
 
Thanks for all the suggestions. Today I got my new PSU. I ended up ordering the AX1200 as suggested in here. But sadly, the PC is acting exactly the same.
 
To me it seems like it is the mobo acting up. Each cold start the SLi is there. If I shut it down without turning off the PSU, one card is gone after next boot-up.
 
I am using the third PCI-e for a Raid card. So I am not sure I can use the powerboost option.
 
Any other suggestions?

1) flash the BIOS again , & set to defaults
2) try a new driver set ( I didn't see you say you did this yet )
3) always possible 1 card is failing yet you didn't test it long enough for the issue to show up.? ( try running 1 card for 1 week, then the other )

You may also want to change PCIe slots as well, or just disconect and reseat, The board assigns resources, and IRQ's and a conflict can cause issues, I just recently was having issues with my 580's in SLI, my mouse was droping out at ramdom, and i was getting display driver fails, removing and reinstalling resolved it, but I had to do it three times, the second time I had some kind of conflict with my raid0 drives, and windows could not start. thgird time I have not noticed any issues yet, some IRQ's and DMA's do not like to share resources.

aka_STEVE_b
 

1) flash the BIOS again , & set to defaults 
2) try a new driver set ( I didn't see you say you did this yet ) 
3) always possible 1 card is failing yet you didn't test it long enough for the issue to show up.? ( try running 1 card for 1 week, then the other ) 

 
 
1) Done it. Went and did it again to make sure by downloading the latest BIOS and burning it to a new CD all over again. Nothing changed.
2) I have tried different drivers, both beta and releases, same issue.
3) I thought about what you wrote here and ended up putting the card that I usually had in the second PCIex slot over in my missus` PC. It has been running there for the second day now without any problems. Her card, also a 480, is now in my PC with exactly the same issue.
 

KMoore4318

You may also want to change PCIe slots as well, or just disconect and reseat, The board assigns resources, and IRQ's and a conflict can cause issues, I just recently was having issues with my 580's in SLI, my mouse was droping out at ramdom, and i was getting display driver fails, removing and reinstalling resolved it, but I had to do it three times, the second time I had some kind of conflict with my raid0 drives, and windows could not start. thgird time I have not noticed any issues yet, some IRQ's and DMA's do not like to share resources.

 
I have tries swapping around on the PCIex slots. Also disabled the HD Audio devices of both gfx cards.
 
I am not sure how to change around on the IRQs with Windows 7 and the EVGA x58 SLI. Any best practice there? In Windows the IRQ change is ghosted when I enter a resource in device manager.
 
With all this I am still leaning towards my initial gut feeling, that the problem is the EVGA X58 SLI mother board. I have also experienced  ( just once during the weeks of swapping around on things) that there is a "no signal" from the graphics card connected to the monitor too.
 
But what seem to be the most consistent behaviour is that the second card disappear after a warm boot. So basically unless the system does a proper POST, the card won't come "online".