On 25 March 2016, 10:34:36 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=296024 by finding the mega prime:
The prime is 1,527,444 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 50th overall. This is the largest known base 5 mega prime. 76 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Steven Wong (mackerel) of the United Kingdom using an Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz with 16GB RAM running Microsoft Windows 10. This computer took about 15 hours 10 minutes to complete the primality test using LLR. Steven is a member of the Aggie The Pew team.
The prime was verified on 29 March 2016, 09:01:18 UTC by Matthew Borneman (Maxwell [MM]) of the United States using an Intel(R) Core(TM)2 Duo CPU E7500 @ 2.93GHz with 4GB RAM running Microsoft Windows 7 Professional. This computer took about 65 hours 5 minutes to complete the primality test using LLR. Matthew is a member of the SETI.USA team.
For more details, please see the official announcement.