Building Computers part 2

Over the holiday break, my 13 year old, Rudy, decides he wants to build a computer. Earlier in the fall he wanted to save up for a laptop, but found the cost to great especially for the specs he wanted. So this was the process:
I wanted this to be his project, but needed to supervise to make sure it would work. I have built computers in the past and work with them today.
Decide on budget. How much money he had after Christmas was over?
I wanted to see a spreadsheet before anything happened.
What did he want for a computer, and do you really need a 1TB hard drive?
All of the parts need to be listed with cost and shipping.
Amazing how many parts you don't know about that need to be bought. He learned
After seeing we were well above budget we started cutting back and doing more research. Found out if he packaged orders from some suppliers, the shipping was lower. We also figured out he did not need a sound card, as he uses headphones while on the computer. Video card was axed until his birthday.

As the parts arrived he installed. One problem is he lives with his mother, and I live about a half hour away from him, so some work was done over the phone, others over weekends with me, or before picking up him or his brother for various activities. I also bought him a simple book on building computers.

Typical phone conversation: "Have the Motherboard installed, power installed and memory. The book says this is a good time to test the bios. I turn it on and nothing happens!"
Me: "Is everything plugged in according to the manuals and book?"
"ummm don't know"
"did you read the manuals"
"no"
"Call me back when you did"

Half hour later another phone call "The bios works!"
"Great, now you can configure the bios and install the drives"
"uhh how do you do that?"
"read the manuals and book"

Using this process he has learned how to build the machine. If I were there, he would not have learned as much, as I would be plugging stuff in and he would wander off.

Tonight we should have the OS installed. I contacted motherboard support in search of missing SATA drivers. Just got the correct drivers, and he can install while I take older brother to robot club. I will teach him how to contact customer service next time. Amazing how much data you need for customer support.

Now back to where this fits in with PBL. This would be the third post this month related to that. He came up with the project himself, asked for guidance, I helped him understand what was needed. He did research on the topic, and then we discussed the research, and he refined his search. During the build phase, he used instructions from various sources and manuals and needed to synthesise this information into new knowledge. When he needed help he asked for specific things. His motivation was entirely intrinsic.

If we let the students choose from a range of topics to do a project, does the project become interesting? How do you best modivate students to do PBL projects,and what works best for you?