That's right. And you an in fact go to www.primegrid.com , get the boinc client, and get crunching. The sieving part is joint sieve for Seventeenorbust, and PrimeSierpinskiProject, so of great overall efficiency.
In something like two weeks, they found more than 1300 factors already, meaning that we eliminate about as many candidates by sieving as by LLR now.
H.