Since I've worked in IT for about 8 years now, I've seen the worst-of-the-worst with Dell's, HP's, Toshiba's and Mac.
The only company who doesn't buy the cheapest hardware is Mac.
All the rest of them skimp in so many areas to save money... as if they didn't save enough by purchasing hardware in bulk...
Their Desktops are barely expandable because of the weak Power Supplies, CPU fans and lack of ports on the Motherboards.
Those three items are the CORE of a computer. Why would you skimp on those?
I've been building my computers for years and always spend the most on the Power Supply & Motherboard. Everything else can be upgraded later on, but if you have to replace the motherboard, it could mean replacing everything else due to advances in technology. If you want to upgrade later on, new parts need additional power, so skimping on Power Supply means purchasing a better one later on.
I understand why companies use Dell and HP, its those warranties and lower costs purchasing in bulk.