Pc being a deliberate pain in the rear...

Hello all, I have one of those issues that probably boils down to computers being evil and out to get you...

I have a Gigabite GA-990x SLI gaming mobo that was running 2 XFX R7870 DD GFX gpus with a crossfire connection perfectly fine for several years and now it just won't...

Both PCIe slots work, both gpus work. They all work independantly, in all configurations, they just won't work together any more.

System:
OS:
Win 10 Pro Version 10.0.14393 Build 14393

Processor:
AMD FX 8320 Eight Core Processor 3.50ghz

Grapics Card:
XFX HD R7870 DD AMD Radeon 7800 Series (x2)

Mobo:
Gigabyte GA-990x - Gaming SLI Bios ver. F1 28/01/2016

RAM:
32gb DDR3 1600mhz

PSU:
Cosair RM750

The Crossfire connector seems fine. Everything is working by itself, all the gpu software has been reinstalled, the BIOS has been reset and neither I nor the PCs (slightly twitching) owner can find any reason or fix for it.

I know its an old system but there must be someone out there who knows the secret,
Have attached a few screen shots from System Information

Help...

 

How old is the PSU? You are running some very old gear, and I am guessing the PSU is just as old? Maybe it can't handle the two Graphics Cards anymore? Do you have a newer PSU you can swap out for testing purposes?

QB

 

Which version of the AMD Radeon drivers are you using for Windows 7?

Is your Windows 7 a 32-bit or 64-bit version?

What are the settings for the two GPUs in the motherboard BIOS? I recall that some versions of the Radeon drivers would not support Crossfire if the BIOS is set to DUAL Graphics mode.

 

Ok, in seeing what would happen yesterday, we updated the system to win 10, burned out all the drivers with napalm and did a fresh install of all the graphics.
It MIGHT be the psu, age = wear, can't argue that but it's a Corsair rm750 and the rig has been well looked after, monitored and kept by it's owner. It's been well used but not thrashed. If there was an issue there, it would get picked up by the monitoring software, yes?
Could it be a psu issue or is it possible it's a windows/BIOS issue? Windows will only see one gpu at a time. Either one, in either slot makes no difference, and I can't find any SLI settings in the SLI mobo BIOS or in the AMD softwear. Am I missing something here?

Dyre Straights, the BIOS is only seeing one gpu, there's enable/disable options but nothing in any of the menues, sub menues and sewers that sugests that the mobo is actually aware of the fact that it is an SLI mobo. There's no dual options, nothing. The AMD programme isn't seeing an SLI mobo, win 7 and win 10 aren't seeing it.That's what is making me wonder if it's a software issue rather than a hardware one...

Update:
During further investigation, the System information/system summery/hardware resources/conflict sharing section is seeing BOTH gpus, at the same time perfectly clearly. Two seperate port adresses, two sperate enteries, both unconflicted and RIGHT F*&CKING THERE! pics attatched

I'm now sure it's a BIOS/windows issue.

 

Thank you for the correction. This is the first time I've had to geek this sort of set up so I'm learning as I go here.

All help is appreciated. We've tried everything on the internet now. Even the silly option of borrowing the flatmates tv and booting the pc with both of them working. Nothing. I am officially stumped.

 

The circumstances are a bit odd i'd say. Specially if nothing was changed and it simply "lost it".

7870's were the last cards that i'm aware of that used the interconnect bridge (the little cable that goes from one card to the other), but i was almost certain that amd made a soft connection possible that made it no longer required on a few of the 7000 series, shouldn't matter either way though.

I've rarely seen the connector fail, but i've read that it can/has for older cards. The bus that controls those connectors can simply stop functioning for no apparent reason.

The other problem can be board related but i honestly don't believe that's likely the case here.

If both cards are being detected, displays can be connected to either card with full functionality, 3D applications can be launched and ran on both cards, then it's not likely a driver/hardware problem.

I do know that newer graphics drivers eliminated the crossfire toggle option in the general settings and moved it to per game configurations, and it's slowly being phased out, which for many crossfire users, it's often best to revert to older drivers if crossfire functionality is being lost, it should also be said that the crossfire AND SLI functions are getting a little tricky with newer version of windows 10.

I doubt power is a problem though.

If you were to get GPU-Z, connect both GPUS either the same monitor or different displays, open up 2x instances of GPUZ and then move one instance to the other display (running on the other card), then make sure the 2nd graphics adapter is selected for the 2nd instance, run the pci-e bus test on both simultaniously to see if both are operating as they should, verify that at least that full functionality is capable of doing both at once.

In the event it does, then it's down to likely the interconnect bridge cable or the bridge contacts/controller chip have failed, or if it doesn't work, there could be a power/board or card issue.

The next option to test is simply install both card in a completely different system, something also capable of crossfire, likely best in a newer system to verify. If the problem disappears then it's something other than the cards in the other machine.

It could be down to the chipset drivers even.



IF a new card is being considered, the current ideal options are often the 570 or 580 graphics adapters, or the 5700's for their current price range and performance leverage.

New cards are due to soon, both from nvidia and amd.

 

The problem is that although both cards work on their own in each of the pcie slots when two cards are plugged in the PC only recognises one.
No options appear anywhere for the second card.
Although in system information it seems to suggest there are two graphic cards connected at two different locations (pic attached) which suggests to me it's a setting in Windows preventing it recognising and installing the second card.

 

Or maybe a sneaky setting in the bios but I have been over and over it and can't find anything relating to it

 

short of powering down and performing a proper cmos reset, there's really no other way but i still doubt it.

If only one card only every works when both cards are installed, this to me would suggest that the other slot simply is refusing to function as intended. I would then say that it's LIKELY a motherboard problem at that point.

 

Although both Pcie slots work fine, I have individually had each card working perfectly on its own in each slot,
It is only when two cards are inserted that the problem starts,
It dosent seem to matter which card is in which slot.
If I install either card in to pcie slot 1 first the second card in slot 2 is not recognised, and if I install either card in to pcie slot 2 first the second card in the first slot is not recognised.
I have tried every configuration and installation order possible.
I have done a complete clean win 10 pro install and full update.
I have updated the Bios.
I have the latest drivers and AMD software.
I have run diagnostic checks on everything and no issues show up.

So to summarise either card will be recognised installed and function 100% correctly in either Pcie slot.
The problem is that once one card is installed (either card, either slot) the second card will not be recognised at all.
The only place the PC recognises two cards is in system information (pic)

 

Have you tried installing an older version of the drivers? They've had bugs in the past so this may have been due to updating to the latest version.
Also worth trying a different Crossfire bridge if you have one spare, though the driver version seems more likely.

 

Yes I have tried multiple drivers and several different versions of the AMD catalyst/adrenaline software.
It is not a driver issue, both cards work perfectly if installed alone.
The issue is the PC not recognising the second card is even there.
It dosent get far enough in the process for it to be the driver or crossfire connector or any other software.
Windows does not recognise second card is present.

Both cards work 100% in either pcie slot.
Both pcie slots work with either card.

If only one card is present in either slot it works 100%.

But no matter which card is installed in which slot the PC will only recognise the first card.
It will not recognise second card is present so cannot install it, I am convinced it's a windows issue now

 

Again this suggests that potentially a motherboard fault has occurred. Testing in a different system to verify crossfire functionality does work would narrow it down.

To me this sounds like a power problem at the motherboard level, or a short/failure on the chipset that controls those pci-ex slots.

On the 990 chipset, the chipset distributes pci-ex lanes directly (unlike modern desktop cpus like intel or amd's ryzen cpus which actively has direct pci-ex lanes to the slots).

suffice it to say, it's a rare situation but not unheard of for the chipset to act up. This of course doesn't eliminate the potential for it to be something in the board itself, as i stated, power problem, could be the power delivery to either slot being insufficient within the board itself, failsafe such as overload protection is "kicking" one of the 2 cards into an offline state. The fact that it still shows up in windows is equivilent to leaving one card disconnecting from external pci-ex 6 or 8 pin connectors reports in windows while the primary card operates fine. Just to clarify i doubt it's the PSU, but it could be related.

If i were to have the machine myself, the first place i'd start is simply swapping power supplies, followed by the mainboard if the psu didn't solve it.

 

I'm curious as to whether power from the PSU to the GPUs is on separate trunks or if a "Y" splitter is being used?

 

It's a corsair RM750 fully modular PSU so each component is plugged in to its own individual socket on the PSU, have tested the PSU and the connectors and it's all good.