I have couple question regarding using the TRM.

OS - Windows 10
AMD Driver version - 21.3.2
Mobo - Asrock BTC Pro v2.0
GPU - RX5700XT from different vendors
TRM version - 0.9.0

Some background here. I have 6 GPUs. If I only use 5 I can set the primary display using IGP on the mobo (in BIOS). But if I use 6 GPUs, the mobo wont post if I try to use IGP as primary display. So I am forced to use 5700XT for primary display when using 6 GPUs.

If I don't connect a display or dummy HDMI dongle, when I start TRM, the GPU0, used as primary display, shows very low hashrate like below.

GPU  0 [33C, fan 43%]      ethash: 1.115Mh/s, avg 1.032Mh/s, pool 0.000 h/s a:0 r:0 hw:0

Once I connect a display or use HDMI dongle, the GPU will start working but with two caveats. Is monitor or HDMI dongle required? 

1) Its hashrate is slightly lower than other GPUs - 56.2Mh (Primary GPU) vs 56.8Mh (Other GPU) in my case. Is this the correct behavior?
2) By default, TRM can only use 7GB vram. If I tried to allocate more vram, the GPU will be detected as dead soon after I start mining. This is correct behavior also?