The CPU cooler is a low profile SilverStone SST-KR01 so that the
power supply would fit. Power is provided via a Rosewill HIVE 650S
650W ATX power supply. The Nvidia EVGA GTX 950 is a ITX form factor
GPU; and thus, the results are with the case closed. The 2 radeon
GPUs are huge and are attached via a PCI-E riser with the case open.
Phoronix Test Suite from Slackbuilds.org; stock KDE; system and test
use default settings. For the RX590, the "HIGH" run references
setting the GPU power management to "high" from the default of
"auto".

    EVGA GTX 590 Nvidia 440.36 kernel 5.4.2
    Radeon HD 4820x2 kernel 5.4.3 Mesa 19.3.0
        radeon (modesetting) 1.20.6
    XFX Radeon RX590 Fatboy kernel 5.4.5 Mesa 19.3.1
        AMDGPU 19.1.0

So far am quite pleased and can't wait to get my hands on a Vega
series GPU, and of course Slackware 15.0 "real soon now."