stability of amd x399 mobo with amd vega cards

[billhinge]

Question, cost aside, is there any additional stability mining with T4 X399 boards vs intel when using multiple Vega GPU's?

My logic was that perhaps the x399 chipset provides more stability and performance being all AMD and multiple Vega's

My main issue with current x170 intel board is stability at speed and random reboots when pushing performance with multiple Vega's
Stability with one Vega isn't an issue though

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[orso.grigio]

I had a nightmare of a time with an Asus X399-A and trying to get more than 4 Vegas on there. The board has 6 total PCI slots (4x16, 1X4 and 1X1). Built a rig on 1950X Threadripper and was running fine with 2xVega56 and 2xVega64. The addition of a fifth Vega, a Vega56 caused a world of problems. The board saw the cards fine, but in Windows (Win10, 64 bit) I encountered problems. The computer would show a blue screen with various artifacts a few seconds after logging in. I tried disabling the 4th card before physically installing the 5th. Everything was fine, but then the same instability/crash would happen when I tried to enable the 4th (of 5 installed) cards from within Windows. This was all on the AMD block chain driver. The driver would not install if more than 4 cards were installed on the machine. On the regular drivers, there was instability on 5 cards as well - less severe than on blockchain driver, but still leading to crashes.

I tried everything...removal of all but 1 card, DDU clean uninstall, block chain driver install on one card, then systematic adding in of additional cards, with shutdown in between each time. I encountered the same thing - on the addition of the 5th card, the system would have the same rebooting/crashing shortly after getting into Windows. No variation of PCI settings in the BIOS that I tried was able to resolve the problem. I trued GEN2/GEN2, GEN1/GEN1, GEN2/GEN1 (and other variations) for the CPU and SB PCIE settings. The BIOS/this motherboard didn't have a '4G decoding' setting, as has been touted for stability on Z170 boards, as seen in other places, here: https://bitcointalk.org/index.php?topic=1808110.20.

I had 2 RX 580s from another system, and opted to swap the Vegas with the 580s. To my surprise, the system was perfectly happy running above 4 GPUs with the 580s. i.e. 5 Vegas + 1 580, or 4 Vegas + 2 580s. Very, very strange. Perhaps someone more talented than me would have found a solution to the problem, but from every angle I considered, there seemed to be a real issue with conflict among the Vegas if more than 4 were present. YMMV, but figured I'd post this here and maybe save someone else from a boatload of grief, or give an opportunity to someone smarter than me to present a solution.

[Miningtry]

Hey bro ever try to mine with 1950X Threadripper? How this cpu perform of new coins only minable with cpu-s?

[billhinge]

Thanks for the reply, now running Asus Prime board with threadripper. Currently got 2 Vega FE  in PCIe slots for solid 5+k h/s poolside cryptonight stable over several weeks at 560W (not optimised and vega soc limited to 1107)

I have 2 further FE not plugged in yet but come easter I will strip them and add my openloop waterblocks to have 4 FE plus threadripper watercooled, aiming for 9 to 10+kh/s. Thanks for the warning on 5 vega 

[orso.grigio]

Miningtry - I get 1450-1470 H/s on cryptonight mining with the 1950X OC'ed to 4 GHz. On one 1950X I get 1455, and on the other I get 1470. Both use liquid coolers and are on X399-A boards. I haven't been great about monitoring the power draw, but it's about 90-100 W above ambient/resting draw.

billhinge - sounds like a boss system in the works  with nice power draw
I've heard the FE are prima donnas in terms of finding setting sweet spots, but absolute monsters in terms of hashrate once you get them all settled nicely. Watercooled Vegas would be wonderful. 4 FE + TRipper should definitely get you to your target.

I've opted to settle for lower hashrates at (hopefully) decent efficiency. Across the 3xVega56s and 2xVega64s I average about 1750 H/s at about 155 W per card (at wall), using OverdriveNTool to set GPU P6, P7 and Mem P3 states (similar to Wattman). I think I could up that 50-100 H/s at similar or maybe slightly lower draw if I spend some time on power tables, but that's an effort for the future. For now, happy to be stable at these rates.