diff --git a/core/chain_manager.go b/core/chain_manager.go
index 1152e3fa22..75d2f6badd 100644
--- a/core/chain_manager.go
+++ b/core/chain_manager.go
@@ -66,7 +66,6 @@ func CalcGasLimit(parent, block *types.Block) *big.Int {
 	}
 
 	// ((1024-1) * parent.gasLimit + (gasUsed * 6 / 5)) / 1024
-
 	previous := new(big.Int).Mul(big.NewInt(1024-1), parent.GasLimit())
 	current := new(big.Rat).Mul(new(big.Rat).SetInt(parent.GasUsed()), big.NewRat(6, 5))
 	curInt := new(big.Int).Div(current.Num(), current.Denom())
@@ -291,7 +290,6 @@ func (self *ChainManager) GetBlockHashesFromHash(hash []byte, max uint64) (chain
 	if block == nil {
 		return
 	}
-
 	// XXX Could be optimised by using a different database which only holds hashes (i.e., linked list)
 	for i := uint64(0); i < max; i++ {
 		parentHash := block.Header().ParentHash
@@ -396,12 +394,9 @@ func (bc *ChainManager) Stop() {
 }
 
 func (self *ChainManager) InsertChain(chain types.Blocks) error {
-	println("insert chain start")
 	self.tsmu.Lock()
 	defer self.tsmu.Unlock()
 
-	defer println("insert chain end")
-
 	for _, block := range chain {
 		// Call in to the block processor and check for errors. It's likely that if one block fails
 		// all others will fail too (unless a known block is returned).
diff --git a/eth/protocol.go b/eth/protocol.go
index b52c7db424..b9b4852928 100644
--- a/eth/protocol.go
+++ b/eth/protocol.go
@@ -253,10 +253,9 @@ func (self *ethProtocol) handle() error {
 	case NewBlockMsg:
 		var request newBlockMsgData
 		if err := msg.Decode(&request); err != nil {
-			return self.protoError(ErrDecode, "msg %v: %v", msg, err)
+			return self.protoError(ErrDecode, "%v: %v", msg, err)
 		}
 		hash := request.Block.Hash()
-		fmt.Printf("received block: %x\n", hash)
 		_, chainHead, _ := self.chainManager.Status()
 
 		jsonlogger.LogJson(&logger.EthChainReceivedNewBlock{
diff --git a/miner/miner.go b/miner/miner.go
index b95c658590..4902964317 100644
--- a/miner/miner.go
+++ b/miner/miner.go
@@ -3,6 +3,7 @@ package miner
 import (
 	"math/big"
 
+	"github.com/ethereum/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/pow"
@@ -29,7 +30,6 @@ func New(coinbase []byte, eth core.Backend, pow pow.PoW, minerThreads int) *Mine
 		pow:      pow,
 	}
 
-	minerThreads = 1
 	for i := 0; i < minerThreads; i++ {
 		miner.worker.register(NewCpuMiner(i, miner.pow))
 	}
@@ -44,6 +44,8 @@ func (self *Miner) Mining() bool {
 func (self *Miner) Start() {
 	self.mining = true
 
+	self.pow.(*ethash.Ethash).UpdateDAG()
+
 	self.worker.start()
 
 	self.worker.commitNewWork()
@@ -53,6 +55,8 @@ func (self *Miner) Stop() {
 	self.mining = false
 
 	self.worker.stop()
+
+	//self.pow.(*ethash.Ethash).Stop()
 }
 
 func (self *Miner) HashRate() int64 {