On 31 January 2014, 9:53:06 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=178658 by finding the mega prime:
The prime is 1,066,092 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 61st overall. This is the largest known base 5 mega prime. 87 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Keishi Toda (yuyusuke@jisaku) of Japan using an Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz with 14GB RAM running Microsoft Windows 7 Home Premium. This computer took about 19 hours and 59 minutes to complete the primality test using LLR. Keishi is a member of the Team 2ch team.
The prime was verified on 2 February 2014 0:15:42 UTC, by smmistak of the United States using an Intel(R) Core(TM) i7-2700K CPU @ 3.50GHz with 16 GB RAM running Microsoft Windows 7 Ultimate. This computer took about 59 hours and 27 minutes to complete the primality test using LLR.
For more details, please see the official announcement.