Remember that people usually won't post their overclocks unless they've gone well; the people that get the 5.0 GHz "golden chips" are the ones who will post about it when they OC. It may be that your chip just isn't perfect (although 4.8 GHz is nothing to sniff at); it may be that your motherboard isn't great for overclocking, which could be due to low power phase count (more power phases usually means less fluctuation in voltage to the CPU, which helps) and/or poor northbridge cooling. What motherboard are you using?
Also, in the mean time don't run it at 1.47V 24/7 (although I'm assuming you aren't), as it's not good for the chip. Also, I'm not a skilled overclocker per se (I dabble), and I know there are some more obscure voltages you can tweak to improve the stability of your overclock; you may want to look for some advanced overclocking guides; this one
isn't necessarily too complex, but notice that they change the CPU PLL, VCCSA, and VCCIO to improve the stability of their overclock. Try changing those a bit, they ought to improve stability