Quote from: flagrant_toaster on January 17, 2018, 02:56:31 AM

Hi,

I'm mining ETH on with a Ryzen5 CPU on the X370-Pro mobo.
I'll admit - probably not ideal as most rigs are Intel and with "BTC" mobos.

In any case I have been able to mine pretty effectively with an RX480 (4Gb) and an RX580 (8Gb) using two PCI x16 slots.
My sum hashrate is around 44Mh/sec @320 Watt with stock cards and some minor changes in Wattman.
Cards sit at ~60 Celsius, which is "ok enough" to me.

The problem occurs when adding a third graphics card [ RX580 (8Gb) ].
I run the card through a riser and then all 3 cards drop to ~18Mh/sec (total 54M/h).
Not sure if it is a dud riser, so I've order a few more that look to be better quality.
I'm currently running the board on a different mobo (8yrs old HTPC mobo, w/ old Intel i5 CPU) and it's hashing even better (24Mh) than either of my cards on the (newish) AMD board (~22Mh each).

I'm after any advice with regard to the following;
- I'd really like to get all 3 cards hashing on my ASUS/AMD board at 24Mh (which I'm seeing on the Intel board).
- I note that a similar board, but made for Intel chips (ASUS Z290) has settings in the BIOS that let me set PEGs to "Gen2"... or some such

.
- I figured I might be able to find the same settings in my BIOS, and [1] that might get my other cards up to 24Mh each, and [2] that might get my riser working as expected.
- Unfortunately these settings don't (appear) exist in the BIOS on the X390 Pro board. (The BIOS actually doesn't have that many options at all, even under the advanced menus).

If anyone has encountered similar, or has tips to further optimise what I'm doing, I'm all ears!
Thanks in advance.

Usually a bad riser causes one card not to work, vs throttling all 3 cards, but this is what I'd do: Remove one of first 2 cards that was working fine, and put the third card in that spot and see what happens. If it works fine, then your GPU is good and the problem could be with the 3rd riser. Then try the 3rd riser in that working spot with working card to see if that still works.

If it does, then it is a system issue with adding the 3rd GPU, vs a hardware issue with the 3rd riser or 3rd GPU.

If it's a system issue, how much RAM do you have? Might be not enough and it's causing all 3 cards to run slower.
Are you running Windows?