M18x R2: 680M SLI suddenly not working, but both cards are detected.

Hey, everyone. I'm so ridiculously frustrated right now...anyway. So, here's the deal: I shut my computer down overnight, then, when I started it the next day, it was as if the graphics drivers had been uninstalled. Like, I literally started my computer and it booted to a state is if no graphics drivers were installed and both GPUs showed with exclamation marks in Device Manager. As such, I reinstalled the latest NVIDIA drivers again, it detected both of the cards, but then it didn't give me the option to enable SLI. I am at a complete loss after having tried all of the following and still not being able to get the SLI functionality to show:

1: Reinstall drivers.
2: COMPLETELY remove all traces of drivers, then install fresh, recent drivers.
3: Completely removing those, then install the drivers that came with the system originally.
4: Upgrading to Windows 8.1 and trying the previous 3. (Tons of drivers showed as incompatible; 8.1 was a nightmare.)
5: Downgrading back to Windows 7 because many of the drivers for this system were showing as incompatible with Windows 8.1. Then, trying 1-3 again.
6: Checked in the BIOS after upgrading to A10, but didn't see anything relating to SLI.

SLI was working just fine prior to shutting down (I know because I played some BF4 right before going to bed). I don't overclock anything except the CPU, and even then, I only have it at the stock Level 3 settings in BIOS (I tried setting it to cTDP for laughs and grins, but it made no difference).

In Device Manager, both cards show under Display Adapters, and both have a status of "working properly." Under "Set PhysX Configuration," in the NVIDIA Control Panel, both cards show as options for using as a PhysX processor.

At this point, I'm completely at a loss. I guess the component connecting the two GPUs to allow for SLI could have gone bad somehow, but before I tear this unit down and disconnect/reconnect everything to determine if something somehow came loose (or if the component is potentially bad), I wanted to see if any of you had any ideas, or if anyone else is experiencing this.

Thanks so much, everyone. This has been the most frustrating day I think I've ever had with PCs. =\

 

Sounds like the SLI cable came lose somehow or just went bad all of a sudden. I would check that before doing anything else.

 

Probably bad SLI cable or loose SLI cable. You can test by removing the SLI cable and booting up, then swap the GPU around to see if they are fine. I did that just 2 weeks ago.

 

I have had my M18x handled unnecessarily roughly a few times by TSA baggage screeners on business trips and the SLI cable got dislodged as a result. Each time the behavior is precisely as you described in the post above. So, I agree with both of the previous posts. Either your SLI cable came loose on one end or the cable has gone bad. Either way, it should be a simple fix. Until you remove the keyboard to examine the situation, there is no way to know if the SLI bridge cable has come loose. If it has not, then you will need a replacement cable.

The part number is GDMRG. If you are still under warranty Alienware will probably dispatch a replacement SLI bridge cable. If not, Google the part number or search for it on eBay. It never hurts to have a spare anyhow, so if you want to have a spare, order one before you disassemble it and then you'll be prepared to replace it if needs to be replaced.

Don't reassemble it before testing. You can simply flop the keyboard over face down on the palm rest and leave the ribbon cables connected. Start the machine and go into Windows to confirm SLI is available. If so, shut down and reassemble.

Alienware M18x Nvidia SLI Cable for Dual Graphics Cards - GDMRG | Parts People << here is an example (although out of stock right now)

 

It seems like that's the issue. Let us know how it goes. If the PC is still under warranty we could help you with the parts needed if you write us to [email protected]

 

Thanks for the replies, everyone! Mr. Fox, I appreciate your detailed response. After taking the keyboard off and testing the cable, I've come to the conclusion that it's bad. I ordered a new one accordingly; hopefully, that's what it is! I'll update this once I receive it and try it.

L_Porras: I'm pretty sure the warranty expired in July, unfortunately. I'm okay with that so long as this part is all that is wrong...lol. I may reach out to you for some ideas if this isn't it, insofar as getting back in with some kind of warranty, if Dell does that after the fact.

Thanks again, everyone!

-Stephen

 

I'm happy to report that it was, indeed, the cable that was faulty! Nice to be back in action. =) Thanks again for the suggestions, everyone!

 

Nice! Glad it was something simple. Thank you for letting us know also.

If you did not already do so, the next time you have it apart, cut some thermal pads into strips the width of the SLI cable and use it to help protect the cable from heat and abrasion. I have never had one go bad on me, but I have done this just for added peace of mind.

This is explained here: How to fix red flickering caused by toasted SLI cable

 

Something like this would help. Having the SLI cable going through copper heatpipes is not good engineering.

 

Man, I really wish I somehow knew about that symptom, because that's EXACTLY what I was experiencing while playing Battlefield 4 when it launched. I'm not sure if you've been keeping up with the train wreck that is the BF4 launch, but suffice it to say, it's unbelievably awful. I thought that symptom was just one of the many, many bugs happening to people with BF4. lol. Oddly enough, though, it only happened in full-screen mode. I had other things going awry with my install which merited a fresh OS installation, so it wasn't a total loss overall, but I had some seriously mixed signals going on!

Such is the price of having a system like this sometimes -- a very small price to pay for ultimate happiness. lol. =)

I'll do that thermal pad strip thing this weekend, too. I did think it was odd that the SLI strip rests on the GPU heat pipes, but at the same time, I wasn't sure if that would really have any impact on the cable. I mean, it *seems* like it might, but I'm not one for putting too much stock in quick correlational observations. I digress, though. lol.

Thanks again for the suggestions and feedback! This is definitely one of the better communities I've been a part of online. =)

 

The reason why it only happened in full screen mode is that SLI often only works in full screen mode. If you run the game in a window, it typically disables CrossFire and SLI. (SLI will occasionally work in window mode, but CrossFire does not.)