Radeon 7950 partial display corruption in Crossfire-X mode

[d3anio97]

[sIDE NOTE FOR THE YOUNG PLAYERS: Radeon 7950 = R8 280... it's the exact same core... just with an overclock! as King_Tuna corrected below, the 380 is a 285 rebadge]

so... I decided to upgrade my rig a little while ago and threw in a GA-970A-DS3P motherboard and swapped out my CPU from an FX6300 to an 8150. alongside that lot, I picked up another 7950 to crossfire with my current Gigabyte Windforce edition one (reason: because it was cheaper than getting a 7970!). I threw the new card in, bridged it, booted up and selectec CrossfireX mode... after that... I got a 50% drop in FPS and every now and again a texture or mesh would corrupt!... add to that the fact that GPU 1 isn't even getting a load when the card is active and there's defo something up!!

here's what I've already done:

check power supply: OK, using an RM750 so it's well within the power and current specs needed for 2X 200W GCN based cards

Run Memtest86 on the RAM: not a single error!

check GPUs individually: both cards handled 3 hours of error checking and performed perfectly

check PCI-e slots the cards were in: again... these worked perfectly. none of them are disabled or damaged. (it's a new board as well, so that helps cut that!

check for driver updates: using 15.8 beta... may drop back if needs be to 15.7WHQL. I also tested on 14.12 which has previously been very stable for me.

the weird bit is that the system is completely stable and doesn't even so much as lock, hang, BSOD or stutter when the cards are crossfired!

as an extra, according to Gigabyte's BIOS specs, as of right now the board I'm using has an up to date BIOS already on it (and the FX CPU support is kinda sorta proving it a bit since this board not only accepts but pushes my old FX6300 to 4.3GHz without a sweat!)

 

[King_Tuna]

[sIDE NOTE FOR THE YOUNG PLAYERS: Radeon 7950 = R9 280 = R9 380... it's the exact same core... just with an overclock!]

 

Let me correct this

 

HD 7950 = R9 280

R9 285 = R9 380

HD 7950 = R9 280 = R9 380

[PlayStation 2]

probably a broken crossfire setup or bridge?

[don_svetlio]

driver 15.7, 15.7.1 and 15.8 have this. roll back. An issue with VSR being added to GCN 1.0

[d3anio97]

probably a broken crossfire setup or bridge?

Wish I could say it was... I used a brand new bridge... gonna try rolling the drivers back and a different model of bridge... according to a couple of modders, the bridge can also sometimes have an effect... although I think that's an NVidia thing and not really an issuse on the AMD side since AMD's limitations for Crossfire are so lenient!

[d3anio97]

Let me correct this

 

HD 7950 = R9 280

R9 285 = R9 380

HD 7950 = R9 280 = R9 380

knew I'd have to derp somewhere with AMD's rebadge this time around... lol it would probably be nicer/easier if they started releasing the GCN 1.2/1.3 cores in the 300 series instead of dragging the same arch over 4 generations... that's just prolonging the inevitable!

[d3anio97]

driver 15.7, 15.7.1 and 15.8 have this. roll back. An issue with VSR being added to GCN 1.0

I'll take a look... I use VSR to drive my display to 1440P  so maybe that could be contributing... I'll try to get 14.12 working on my system (I had them working on Windows 10 before using a Windows 7 driver in compatibility mode... Linus would probably say it's janky as all balls but heck... it worked first time so why not do it again!!)  and I'll report back if it fails and the second bridge I've ordered doesn't fix the issue... which should be a killer since I've had both cards do 24 hours of benching, compositing and stress testing with not a single error!

[don_svetlio]

knew I'd have to derp somewhere with AMD's rebadge this time around... lol it would probably be nicer/easier if they started releasing the GCN 1.2/1.3 cores in the 300 series instead of dragging the same arch over 4 generations... that's just prolonging the inevitable!

GCN 1.3 doesn't exist as of now.

 

I'll take a look... I use VSR to drive my display to 1440P  so maybe that could be contributing... I'll try to get 14.12 working on my system (I had them working on Windows 10 before using a Windows 7 driver in compatibility mode... not the best idea but by 'eck does it work!)  and I'll report back if it fails and the second bridge I've ordered doesn't fix the issue... which should be a killer since I've had both cards do 24 hours of benching, compositing and stress testing with not a single error!

Wait? Windows 10? Yeah, no. That explains it. MSX is unstable as fuck at the moment. Driver 15.7.1 is as close as you can get it to being stable with CF

[d3anio97]

GCN 1.3 doesn't exist as of now.

 

Wait? Windows 10? Yeah, no. That explains it. MSX is unstable as fuck at the moment. Driver 15.7.1 is as close as you can get it to being stable with CF

I know it would be cool if it did... kinda hinting that it should have long since existed by now :3

[d3anio97]

UPDATE:

Got a new set of bridges and I did a clean install of Catalyst 14.12... all's seeming well since the corruption's gone and I'm seeing better framerates than using a single GPU... (ALMOST double... just what I wasn't expecting!)