I did my first show on a system, it tested well, but we had some significant issues during the show, one I've never experienced on other shows before


The setup: 2 cams SDI on Blackmagic DeckLink Duo and 1 HDMI/SDI output via Mini Monitor, instant replay of 2 cams, 4 keyers on.
The PC: Intel i7 8700k, Gigabyte Z370 Gaming 5, 1TB NVME for replay, 500gb SSD for record, 250GB for boot, GTX 1060 GPU

The issues:

1. Recording H264 with hardware acceleration added about 35% CPU usage. With stream and recording and replay recording, I was about 50-65%, as soon as I record the show, CPU usage jumps to 100% and the stream button flashes.

2. Replay when playing does use significant CPU. after the above instance, I stopped recording, and when cuing or playing back a replay, CPU again spiked to 100%.

I noticed that while vMix reported 100% cpu, the windows task manager itself only reported 50% or so, but a clock speed of 1.5-2.5Ghz, despite the i7 8700 being almost 4ghz.

I've built 4 of these systems, and none of them have this issue, so I'm thinking I must be doing something backwards, a system built to the reference system spec should be able to handle 4 cams, replay, recording, and streaming at the same time.


Any ideas where I can start to look?