(Moved from the tech support forum...)

My motherboard of choice for mining (ASRock 870 extreme 3) can't sustain the heat of two 5970 (~90°C).

I fried two of these already (actually, the PCIe-related capacitors somehow melt). I thought I had been unlucky with the first one, but apparently it's a weak point of the model (which is advertised for its durable capacitors, oh the irony).

Do you have a recommendation of a reliable, dual PCIe x16 motherboard?

May be MSI 790FX-GD70 Winki Edition will fit to?

I have got MSI 790FX-GD70 Winki Edition / ASUS M4A79T Deluxe, the cards are inserted in the distant slots + PCI-E x16 riser - for the third card...