Two AMD Radeon RX470 8GB in one case - one gets 290 H/s and second only gets 65 H/s

Two AMD Radeon RX470's 8GB in one rig/case - one gets 290 H/s and second only gets 65 H/s .. is this normal or what would be some guesses on how to get the second GPU to perform better. Motherboard and CPU are not new but are Core 2 Duo 3.0 Ghz, 6GB RAM. Anyone have any thoughts? Thanks

Using Claymore's Windows GPU mining software

Maybe you should check the BIOS options, there might be something about how the second PCI-E slot is communicating with the device. It is usually recommended to have it on "PCI-E x 1".
Hope this will help.

how do u enter your rig? Remotely? if yes, plug a dummy adapter into the GPU making 65H/s and you will get the full speed. Check the clock speeds of the GPU making 65 H and you will probably see 300/300 Mhz.

There were no BIOS settings but the fake monitor did the trick ... I plugged in a display port from my KVM switch while booting the rig and now both cards are hashing at about 300 each. Thanks again!!

Check the clock speeds of the GPU making 65 H and you will probably see 300/300 Mhz..... I am building another rig and having it reboot when I load up Claymore's miner

How do I change the clock speeds so they are not 300/300Mhz?

It also reboots randomly ... This is a fresh install of Windows 10 on new motherboard, CPU, Mem, and graphics cards Radeon RX480 ... one is made by MSI and the other is Gigabyte ... could this be the problem? Do the graphics cards need to be the same in the same chassis? I can reproduce the problem by opening the miner software ... it gets half way thru its initial setup and then just reboots .... any advice would be helpful.

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random card from different brands could cause a problem, since all of them have a little bit different BIOS and different voltages for core and memory. Even with same brands they could have different BIOS. First of all check if the riser cables are ok and if energy split from the PSU is correct. In most cases PSU is the problem? What kind of PSU and wiring do you have?
After you check with PSU you should check for a custom BIOS with custom memory shifts for whatever currency you would like to mine. There are a lot of FAQs on how to modify and flash your GPU BIOS.

After (or not) flashing the cards with custom bios you need to play with settings of core/memory speed and voltage. This is a tricky part, because each card has different memory and ASIC quality. Its best to test each card per time and see what is possible to reach with settings.

Plug in the hdmi cable in the gpu showing 65h/s
It will come back online :slight_smile:

If the two cards are next to each other in the chassis, the problematic card might not be getting the air cooling it needs, thus causing it to ramp down its performance automatically. You might want to separate the cards from each other (if your chassis allows this) or use a riser to move the affected card out of the chassis.