But in the book "How We Test Software at Microsoft", they mentions Microsoft test USB implementation with "USB Cart of Death", which including 10 of 8 port usb

But in the book "How We Test Software at Microsoft", they mentions Microsoft test USB implementation with "USB Cart of Death", which including 10 of 8 port usb hub: https://books.google.com.tw/books?id=X5lCAwAAQBAJ&pg=PT414&lpg=PT414&dq=%22USB+Cart+of+Death%22&source=bl&ots=v0qBrqEGpY&sig=ACfU3U1shLj1hod6ohurBzXNjoWMl6anoQ&hl=zh-TW&sa=X&ved=2ahUKEwjYm5b51_nrAhX_w4sBHT5uDxYQ6AEwAnoECAEQAQ#v=onepage&q=%22USB%20Cart%20of%20Death%22&f=false https://books.google.com.tw/books?id=X5lCAwAAQBAJ&pg=PT414&l... Edit: Maybe it is no issue with USB hub, but not work with too many usb controller (USB port to MB directly)?