When SBIOS finishes POST, it tells driver by writing an register.
直接翻译：当系统SBIOS 完成提供开机实时测试(Power On Self Test)时,系统SBIOS 就会通过写入登记/注册来通知驱动器.
你的意思是（按照你对原文的理解）把【“,“当sbios完成post自检后,sbios通过写一个寄存器告诉驱动”这个方案比较好”】这句话翻译成英语.
好吧,应该是：
When SBIOS finishes POST, it tells driver by writing an register, which is a good solution .
说明：至于什么时候用that从句是根据句子上下文之间的关系来确定的,不是非得根据语法去生搬硬套的,套好了可以“拿来主义”,否则,顾此失彼啊. 如果一定要用that从句,那么就可能需要改变原文结构,写成： that SBIOS tells driver by writing an register after finishing POST should be a better solution .
或者：it is a good solution that SBIOS tells driver by writing an register after finishing POST .