Last week, there were 1,145 blocks rewarded to miners, according to the Neighbourhood Pool Watch. Based on the recent price of BTC times the 25 coin reward, that's more than $12m.

At bitcoin's current price and network difficulty, the network is generating millions of dollars per week. But that's with miner operating costs notwithstanding.

For example, Dave Carlson's MegaBigPower pool earned 18 blocks last week, representing 1.57% a share of total rewards. That's about $200,000, and some of those spoils will need to go to running the datacenter that supports his pool.

With that in mind, here is what has been going on in the mining sector since our last roundup.

Using Radeon R9 280x GPUs to mine scrypt is becoming fairly inefficient due to the rise of the Gridseed miners. One enterprising DIY miner has decided to remove heat by dipping his GPUs in mineral oil, then extracting the heat using a car radiator.

There are a number of cooling options available for mining: Air, water and the use of treated fluids to cool miners.

Mineral oil is an interesting option, not only because it looks unique - you can see heat dissipating off of the oil - but also due to the fact that it can be quite messy. Nevertheless, it does work and miners building their own custom rigs are clearly using it to reduce heat generation.

San Francisco-based HashFast, a mining designer and manufacturer, has been having a number of problems. It recently had to lay off half of its staff and told Ars Technica that the company is broke - although they have denied bankruptcy rumors.

"The only thing that is holding us back is that we are as poor as church mice," CEO Eduardo de Castro said.

HashFast had reportedly taped out a 28nm chip that could hash at 400GH/s last September. However, the company has had a number of problems. For example, in March the company had its bitcoin wallet frozen by a Fort Worth, Texas court.

In a guest post by Dario Di Pardo for CoinDesk about purchasing mining equipment, Di Pardo wrote he had lost confidence in the company, and has requested a refund.

ASIC scrypt mining is heating up, and perhaps the best example of this is Innosilicon's A2 Terminator.

The 28nm chip is capable of operating at a minimum of 1.6MH/s per 10 watts. That means a 150MH/s unit would use 1KW. Innosilicon, a Wuhan, China-based manufacturer, will sell these chips to makers of complete mining rigs.

One of those companies is Gridseed, one of the first producers of scrypt-based mining units. Gridseed has told CoinDesk that it already has built a blade form factor unit using the A2 Terminator called the G-BOX.

The Gridseed G-BOX is expected to produce 70MH/s of scrypt power per unit. That would be a major step up from Gridseed's current G Blade, which hashes at 5.2MH/s while using 140W.

China-based Bitmain, which has reportedly been delivering on its shipment promises, will offer its existing Antminer S2 customers an upgrade. The company is currently selling the Antminer S2 units with 1TH/s of power at 1.2KW.

However, a recent Bitcoin Talk forum post indicates that the company will sell upgrade packages to these units that could double the S2's power to 2TH/s, available this fall.

Bitmain's only other product right now is the Antminer U2+, a USB stick that generates 2GH/s at 2.95W. It is selling a minimum order of 500 U2+ units for 10.8. Bitmain also seems to have an agreement with 112 Bit, a US-based distributor of Bitmain products, to provide hosting for the company's hardware.

Kansas-based ButterflyLabs has released an update on its Monarch blade form factor miner. The 28nm unit, which is expected to perform at 600GH/s for $2,196, is said to have better power performance over its industry rivals.

According to the update, the Monarch will be three-to-five times more efficient than the competition. The base Monarch is expected to draw 235W of power, and another version, called the Imperial Monarch, will have 1TH/s of power at 550W.

Although the Monarch's initial test chips were produced back in January, shipment of units has been delayed. Recently, it was reported that consumers have appealed to the Federal Trade Commission to investigate over $1m in alleged unfulfilled orders from BFL.

Canada-based Flow Technology is focusing on scrypt - and also scrypt-n, which has been supposedly ASIC-resistant. The company's $7,900 rack-mount Liliac unit is expected to hash at 300MH/s at 1.8W per megahash. The units are scheduled to start shipping in Q3 of 2014.

The company does have two other products for scrypt mining - a 10MH/s standalone unit called the Daisy and a 60MH/s blade called the Orchid. However, these units also have a Q3 2014 target ship date.

There are now a number of coins promoting themselves as protected from ASIC mining because of scrypt-N including vertcoin. But if Flower Technology is able to produce a miner that can hash both scrypt and scrypt-N, that could have some serious implications for the altcoin mining market.

Got a cryptocurrency mining tip for future roundups? Contact us.

Disclaimer: This article should not be viewed as an endorsement of any of the companies mentioned. Please do your own extensive research before considering investing any funds in these products.