Bitcoin wallet using CPU

I had the same issue on Win8 with Bitcoin Client v0.8.5-beta, and was able to solve it by turning off "gen", but there was no bitcoin.conf file on my system and had to create it manually myself at the following location:

D:\Users[user name]\AppData\Roaming\Bitcoin\bitcoin.conf

Inside the file simply include:

gen=0

Once you save it, restart the bitcoin client, and if you have the same experience I did, you will notice cpu go down to near 0, even during sync.