Instruction: First, identify the target attributes from the provided list. Then, scan the product title, description, feature, and brand to extract the values associated with each target attribute. Finally, create a list of dictionaries, each containing the extracted attribute, its corresponding value, and the source where it was found.

Input:
Product title: ASUS M51AD-US002S Desktop (3.1 GHz Intel Core i5-4440s Processor, 8GB DDR3, 1TB HDD, Windows 8) Black (Discontinued by Manufacturer)
Product description: Fast. Powerful. Reliable. The M51 desktop is powered by a 4th gen Intel Core i5 processor and discrete NVIDIA graphics to deliver incredible performance. Built with more innovation per inch than you could ever expect from a multimedia powerhouse PC, experience the versatile desktop PC that is built to be about you.
Product feature: Intel Core i5 Processor 3.1 GHz( cache), 8GB DDR3, 1000 GB 7200 rpm Hard Drive, Windows 8
Product brand: Asus
Target attributes: Processor Speed
Answer: attribute: processor speed
value: 3.1 ghz
source: product title
attribute: processor speed
value: 3.1 ghz
source: product feature