▁aware ▁mother boards ▁usually ▁had ▁a ▁few ▁extra ▁cache ▁control ▁lines ▁to ▁maintain ▁cache ▁coh er ency , ▁as ▁well ▁as ▁CPU ▁register ▁control ▁in ▁the ▁B IOS ▁to ▁enable / disable ▁the ▁on - board ▁cache . ▁Cy rix ▁later ▁released ▁a ▁clock - double d ▁" direct ▁replacement " ▁upgrade ▁package ▁for ▁ 3 8 6 D X ▁systems ▁called ▁the ▁C x 4 8 6 DR u 2 . ▁This ▁k it ▁included ▁a ▁standard ▁ 4 8 6 D LC ▁with ▁an ▁extra ▁" ding us " ▁that ▁sat ▁between ▁the ▁CPU ▁and ▁socket ▁and ▁provided ▁the ▁control ▁lines ▁for ▁cache ▁coh er ency . ▁These ▁k its ▁were ▁quickly ▁su pers eded ▁by ▁the ▁C x 4 8 6 DR x 2 ▁CPU , ▁which ▁integrated ▁the ▁cache ▁coh er ency ▁circuit ry ▁into ▁the ▁CPU ▁itself . ▁The ▁C x 4 8 6 DR x 2 ▁appeared ▁on ▁the ▁market ▁in ▁ 1 9 9 4 , ▁by ▁which ▁time ▁the ▁ 4 8 6 ▁was ▁already ▁being ▁disp la ced ▁by ▁the ▁Pent ium . ▁Sales ▁were ▁poor ▁due ▁to ▁the ▁high ▁price ▁and ▁the ▁under wh el ming ▁performance ▁compared ▁to ▁a ▁true ▁Intel ▁ 4 8 6 D X 2 . ▁It ▁was ▁often ▁che aper ▁to ▁purchase ▁a ▁new ▁ 4 8 6 ▁mother board ▁than ▁to ▁invest ▁in ▁an ▁upgrade ▁CPU . ▁ ▁References ▁ ▁C x 4 8 6 D l c <0x0A> </s> ▁The ▁ 2 0 1 6 ▁Patri