I repair PCs for a living so I see computers of all ages come in. Sometimes I see $300 wal-mart specials that are 10+ years old coming in for simple memory or hard disk upgrade/replacements. Sometimes I see brand new models. Every machine is going to have a lifespan that directly correlates with the owner. I personally have a 12 year old HP laptop that still runs strong... not that I use it for more than HDD diagnostics.
As far as an Apple PC over a Windows PC? They both have the same failure rate. Apple laptops have thermal issues that cause the logic boards to fail more often than a Dell or HP. Dell and HP consumer grade laptops are basically ewaste, professional grade are actually robust. Asus builds by far the most durable laptop for the money right now. Lenovo Thinkpads? Although they get expensive they are built like fort knox and it's a rare treat when I have to repair one.
I don't suggest anyone gets a laptop/notebook unless they are a traveling professional or student. Most people who own laptops damage them in some form within 6 months.
With all of that said, I highly suggest you prioritize what you actually need. If you require a laptop don't jump to any one brand off the cuff. Asus and Lenovo are the only brand of Windows PCs I buy. I'll never own a Dell, Gateway, Acer or HP. They are poorly built. Apple makes a super solid PC that has the potential to last for years. They are kind of hit or miss. Some people never maintain them in the manner I'd consider "properly" and they last for years. The folks who do clean the fans, heat exhangers and replace thermal compound almost never have a problem.
If you're going to invest in a laptop be prepared to spend at least $1000. I suggest staying away from the Renta tier of Macbook Pro due to it's astounding lack of repairability. The Macbook Air is just barely able to be repaired, but expect a huge bill. If anything try to get ahold of a Pro with the matte display. If you opt for a Windows PC definatly look at Asus and Lenovo's offerings, but make sure you're looking at $900 + machines.
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It's not the work you are doing or the chipset, it's overheating. Replace your thermal compound and think about buying another underside case panel. Modify the panel to allow the fans to breath. The heatsink and heat exchangers are a bit too small to deal with the TDP of that AMD gpu, in the stock configuration. Do some quick, cheap modifications to your laptop and the problem will go away.
Sorry for the double post.