Is it still possible to mine for bitcoins using a normal desktop computer nowadays?
You can use your normal computer mine bitcoins, I did use GUIminer to mine in my computer, it is working and it is great. But the problem about this is it's profit, don't expect to have a lot of profit from these type of mining because it is not really profitable.
theoretically, you could mine bitcoin blocks using pen and paper... But personally, at current day and age, i would never say that you can use a cpu to mine bitcoins to a newbie.
Saying that you succesfully mined bitcoins using GUIminer might lead new users to the conclusion that this is something they could do.
If you re-read my first post in this topic:
https://bitcointalksearch.org/topic/m.17790187 you can see that if you a server with XEON dual core CPU's AND 6 GPU's, you'll make $11/year BEFORE having to pay your power company and BEFORE having to pay for hardware/repairs.
I did the calculations for an i7 (wich is currently found in high-end desktop pc's):
http://www.coinwarz.com/calculators/bitcoin-mining-calculator/?h=0.02&p=130&pc=0.00&pf=1.00&d=422170566883.83700000&r=12.50000000&er=1042.04050000&hc=0.00The earnings per year are so small coinwarz doesn't even register them, so less than 0.5 cent/year (that's < $0.005/year), but you'd be burning +130Watt 24/7 to make less than this half a dollarcent a year... So imagine your face when you receive the powerbill for mining this 0.5 cent/year...
At current diff, it would, on average, take you 1049310635 days to mine a block with an i7 CPU mining at 100% 24/7, that's about 3 million years. Since the diff is rising, the time to mine a single block will even be a lot longer in reality.Mining with your CPU in 99.99999999999999999% of the cases will result in negative profit, even with free power! The chance of hitting a block with a cpu is smaller than the chance of winning the lottery, but the earnings from a lottery win are much higher, and the ticket price is lower.
So, altough it's THEORETICALLY possible to mine bitcoins with a CPU, please don't make these statements because they'll confuse new members.