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Graphics Cards

Adept I

Dual GPU issues on X399

I just got 2 Vega 64s and installed them in my system.  It seems to cause nothing but problems.  I reinstalled windows and it seemed to work better for a while.  Games ran very poorly until I switched the ddr bank interleaving from auto to channel.  I was happy.  Everything was going great.  I started installing a bunch of games and then the system just ground to a halt.  No matter what I do the system is "working" but unusably sluggish. (like mouse will move every couple of minutes.  I've tried everything I can think of and it all seems to center around the hard drive being accessed.  System works in safe mode but any number of applications running is enough to slow it to a halt.  Removing one video card completely fixes the problem.  When the system is being sluggish I also get alerts from raiXpert2 that an array has been disconnected and then inserted.  It feels like there are not enough resources of some sort but I havn't been able to figure out what.  I have tried different settings for the PCIe slots switching unused ones to NVME raid mode.  I figured I would check here in case I'm just doing (or not doing) something really stupid before I give up and resign myself to only having one awesome GPU. 

System Specs:


Amd Threadripper 1920X

Corsair Vengeance RGB LED 32GB (4x8GB) DDR4 3333 (PC4-26600)

Corsair AXi Series, AX1500i, 1500 Watt (1500W),

Samsung 960 PRO Series - 512GB PCIe NVMe (3 of them set up as a raid 0 boot drive)

ROG STRIX RX Vega64 8GB OC (1 or 2 depending on if I want to actually use the computer.  LOL)

8 Replies

are the Vega 64 air cooled or Water cooled?

According to this website : PSU REQUIREMENTS - RealHardTechX

Two Air-cooled Vega 64 requires a minimum PSU of 1100 watts

Two Water-cooled Vega 64 requires a minimum PSU of 1500 watts

So with one Vega 64 GPU card installed, the computer works normally but with two it becomes extremely sluggish. What does Task Manager - Performance Tab show for CPU, GPU & Memory usage with one and with two vegas installed?

Do you have any hardware monitoring software installed like HWmonitor that will indicate PSU voltages and Temperatures of CPU and GPU?

Adept I

They are air-cooled.

PSU is 1500w

Task manager doesn't show anything really (when you can get it open) .I wasn't kidding about it being unusably slow.  It's impossible to use when the mouse moves speraticly a few pixels a minute.


There is this very long thread here on AMD Forum concerning mouse lagging or stuttering : AMD Radeon Software 18.5.1 freezes my computer every 5 seconds .

Adept I

Thank you.  However I don't think this is the same issue.  For one it only occurs with dual GPU and its not just the mouse.  The whole interface slows down. You can see this especially when it's booting.  It's not just a laggy mouse.  It's more like it's almost frozen.


Okay, I was just trying to direct you on what you posted. I really not that familiar with Vega 64.

Trying contacting AMD Support by opening an AMD EMAIL SUPPORT Ticket from here: Email Form

This way you will get an answer from AMD Support directly. Maybe they can direct you on how to resolve your problem.

Do you believe it might have something to do with RAID being used?

Are you, by any chance, seeing very high temperatures with dual GPU installed?

Adept I

Thanks.  I'll try the support email.  Temps on the cards stay reletivly low (50-70)

It feels like it's related to the raid.  Like there arn't enough "slots" for something.  There should be plenty of pcie lanes 3*4 for the M.2 drives and 16*2 for the GPUs = 44 lanes.


I not sure, this may be helpful in how your  PCIe lanes are configured on your motherboard through BIOS according to your Motherboard Manual:

Found this thread at Superusers concerning about M.2 PCIe SSDs and how it affects PCIe lanes: Does M.2 SSD Card mess with PCI express? - Super User

It is possible, guessing here, that the two Vegas are not getting enough bandwidth when installed in a RAID Configuration. Best to ask AMD Support unless someone else here at AMD Forum can explain.

Download and run GPU-Z. That will tell you what PCIe speed both cards are running when installed.

Click on the Blue Question mark next the PCIe Bus Interface and click on Render. This will show the proper speed that is running at it highest performance.

When I used the Render Test, the PCIe Bus Interface went from 1.1 to 2.0