How your manager chooses to interpret this action is up to him and there's no way we can no for sure. However, in my experience, people managers are mostly concerned with making sure their team has the tools they need to deliver quality work in a timely manner. If the head of purchasing has agreed to the SSD upgrade, I don't think it's likely that your manager will care all that much. If it were me and I felt that the SSD would help me deliver work faster, I would go ahead and say yes. Of course, it's important to take into account the type of relationship you have with your manager and how they've reacted to these types of things in the past.

How your manager chooses to interpret this action is up to him and there's no way we can know for sure. However, in my experience, people managers are mostly concerned with making sure their team has the tools they need to deliver quality work in a timely manner. If the head of purchasing has agreed to the SSD upgrade, I don't think it's likely that your manager will care all that much. If it were me and I felt that the SSD would help me deliver work faster, I would go ahead and say yes. Of course, it's important to take into account the type of relationship you have with your manager and how they've reacted to these types of things in the past.