I’ve had the opportunity to try this out first hand at the Gigabyte OC Workshop this Monday, with the TeamAU crew (dinos22, deanzo, and uncle fester). LN2 overclocking on the Z68X-UD4, Core i5 2500K, GTX470 and the GTX580 SOC.

How does it work?

The reason why LN2 cooling works so well is not just because we’re pouring really cold liquids onto the heat source; it’s also because a lot of the heat energy is absorbed by the process of evaporation. To make sure that the LN2 doesn’t just boil away and splatter away, there are custom designed CPU "pots" that are essentially a heatsink base with a cup to hold the LN2 while it evaporates.

I’ve been told that the colder the CPU gets, the faster it can run. (That, and to save the CPU from blowing up from pumping an insane core voltage into it.)

Why is sub-zero overclocking more difficult?

The biggest difference between the conventional air cooling and even cooling below room temperature is that condensation builds up as moist air settles on the cool surfaces on the equipment. As we all know, water and electronics don’t mix. That’s why we see so many fans, hairdryers and mounds of paper towels in LN2 setups.

Given that the CPU can only be overclocked so much below a certain temperature threshold, on the one hand we need to keep the CPU below a certain temperature, while on the other hand we can’t drop the temperature too much otherwise we’d get what’s called a "cold bug" and the computer would freeze – as in, lock up and stop working.

Usually when the computer locks up, it’s easy enough to hit the reset button to reboot and try again, but with subzero cooling there’s also the "coldboot bug" where there computer will not start unless it’s warmed up above a certain temperature. I suspect the coldboot bug is due to arithmetic underflow on the temperature sensor that falsely triggers the thermal protection circuit. The quickest way to fix this is apparently putting a butane torch to the LN2 pot…

Because temperature and voltage regulation is so critical, external temperature probes are used to get to most accurate readings from as close to the chip as possible. We can’t rely on the built-in sensors because they’re not designed to operate at extreme subzero temperatures, and many motherboards are simply incapable of reporting temperatures at that range.

What are the risks?

As mentioned before, the biggest risk in going sub-zero is the build-up of condensation wherever that’s colder than ambient. There’s a good amount of preparation work to be done before anything is plugged in, including insulating exposed circuitry on the motherboard against moisture and the cold, as well as making sure that the cooling device and temperature probes is mounted correctly.

Even when all precautions are taken, things can still go wrong. We were shown a dead $600 GTX580 SOC with a resistor gone kaput.

The Gigabyte OC Workshop

The workshop was an incredibly fun experience, and it’s a rare opportunity to have the professional overclockers share their insights and experiences as well as an excellent tutorial on LN2 overclocking.

It’s a shame we didn’t beat any records on our first try, but I did walk away with a Gigabyte X58A-OC Motherboard having guessed the closest top 3DMark11 score. The runner up (Justin) walked away with a Gigabyte Z68X-UD4-B3 Motherboard.

Final words

A big thanks to PC PowerPlay and Gigabyte for hosting this awesome event. It’s incredibly difficult to even have a go at LN2 overclocking because it’s just a different beast. Reaching out and teaching us how it’s done really saves the stress of not knowing what’s right and would definitely save a bunch of dead hardware.

Let’s do this again!

On Tuesday, as part of the Dean’s Lecture Series, Microsoft’s Chief Research and Strategy Officer Craig Mundie demonstrates a virtual persona based teleconferencing technology known as Avatar Kinect which was announced at CES 2011 earlier this year.

This public demonstration was the second in Australia after the Melbourne event a day before, and was in attendance of over 300 people in Sydney, a hundred more than the first.

The lecture focused on next generation computer human interaction interaction “Natural User Interfaces” (NUI), set to expand the possibilities of sterile computer control in the operating theatre, remote virtual gaming and a virtual receptionist. Natural user interfaces is set to remove the learning curve from today’s user interfaces, taking advantage of metaphors from the physical world.

Craig explains that while the step from telephone was to television, the next step is telepresence. I think that the use of an avatar is a great step forward, especially since many of today’s users are already comfortable with taking upon an online persona through many of the video games available today.

Microsoft Research have been rather active in NUI development, and many of its work could be found found explained in quite simple terms at MSDN ‘s Channel9 since TechFest 2010.

So what exactly is the problem? The screen develops a number of permanently grey pixels, so that no matter what colour those pixels needed to display, they’ll always show up as grey.

No, it’s not a cracked screen – the glass touch input panel is fine. The LCD is not cracked, it’s just dead pixels. What’s worse is that those dead pixels are somewhat contagious. Those grey lines would extend until it reaches the edge of the screen, killing off more and more pixels in due time.

Now if you’re unfortunate enough to have this same product defect as I did, the obvious question is, "How can we fix it?" I asked the Apple store, and they were willing to fix it for me – for about AUD $200. Well why might I want to get Apple to fix it for me at that price, when I could almost get a brand new iPod Touch?

There are sites out there that claims to fix iPhone dead pixels, but it certainly won’t fix this particular problem. You see, it’s a physical degradation, which can be seen under bright sunlight, even when the device is powered off.

If I’m not willing to pay 4/5 of the price of a new one to fix an old iPod Touch, what are my options? Throw it away? Nope. Here’s my plan. use it with the defect until it becomes annoying enough. Then, I’ll buy a replacement screen on eBay for about $AUD 15 (with free shipping) and fix it myself. Hah – take that, consumerism!

Throughout this year, I was busily working on my undergraduate thesis project, with the goal of developing a software based transmission system for satellite TV. In particular, I wanted to implement the European standard DVB-S using a general purpose computer and the free software radio framework called GNU Radio and a generic radio device called the USRP from Ettus Research.

How did I go? It worked! I was able to correctly decode the captured signal from the satellite and recover the MPEG-2 transport stream that can be played using MPlayer, but unfortunately that’s not the end of the story. Ideally we’d like to receive the satellite signal and decode it in real-time, but our processing speed hasn’t quite got there yet. The performance can be summarised in the figure below:

In this chart, we’ve taken the throughput of each component signal processing block in the receive chain and normalised it to a value of 1 meaning that it’s just able to run in real-time assuming that each block can be run in parallel. A value of lower than 1 means that it’s slower than real-time while values greater than 1 mean it’s more than fast enough for real-time processing. Looking at the proportion of CPU time spent in decoding, there are only three blocks taking up most of the time: the Viterbi decoder, the M-PSK receiver for symbol timing recovery and the frequency correcting frequency locked loop:

So what we need to do now is improve the efficiency and throughput of each of those blocks, then we should be well on our way to real-time, satellite TV decoding on completely generic and reconfigurable software radio on the computer!

More details can be found in my treatise, which can be found under my blog’s Sydney Uni page.

Reader contribution

Simon’s tried out my code to see if it’ll work on a newer inverter, the CMS-5000. Unfortunately the library as it stands doesn’t quite work. So let’s take a closer look at the packets:

First we reset the inverter:

SEND -> aaaa 0100 0000 0004 00 0159

Discover inverters:

SEND -> aaaa 0100 0000 0000 00 0155

RECV <- aaaa fe00 0000 0080 0a 52353634363033303631 04fd OK

Mostly OK so far, but something that strikes me is that the first byte (0xFE) of what I assumed to be the source address seems to have some other significance (it’s not 0×0000). Moving on…

Register the inverter with address “0001”:

SEND -> aaaa 0100 0000 0001 0c 523536343630333036310001 0384

The inverter acknowledges

RECV <- aaaa fe01 0000 0081 01 06 02db OK

So even though the first byte of the address 0xFE is incorrect, things still seem to be working.

Now we try to find what status fields the inverter gives:

SEND -> aaaa 0100 0001 0101 00 0158

RECV <- aaaa fe01 0000 0181 01 15 02eb OK

This bit here is the interesting bit. First, (if my assumptions about the comms protocol were correct), the inverter only gives 2 fields: 0×01 and 0×15. That’s really few compared with the ones I’ve seen before. Not only that, but we don’t yet know what the field 0×15 is for. Basically I assumed that the reply I get is a listing of the status fields, but instead I get something else.

So let’s query the inverter for its status:

SEND -> aaaa 0100 0001 0104 00 015b

RECV <- aaaa fe01 0000 0184 12 05dc003c071c0abe1290139a009900e8034a 080f OK

So here we have the full status update from the inverter. We can’t decode what it’s saying, because it doesn’t quite match the status field query. This is why the pv library is failing to interpret this packet based on the received structure that was supposedly just 2 fields long.

What does this mean?

In the most basic level, there are a few assumptions + generalisations that I’ve made which turned out to be inaccurate, hence it’s not working for a different model inverter.

What we’d need now is a capture of the raw communication between the official monitoring software and the inverter to get a better understanding of what’s going on.

So, I went and bought the module, cracked the netbook open and added Bluetooth, all without spending truckloads of money.

Why Bluetooth?

Why do I like Bluetooth so much? I use it to connect my Microsoft Bluetooth Mobile Keyboard 6000 (it’s a fantastic piece of hardware), my Microsoft Bluetooth Notebook Mouse 5000 and my Microsoft IntelliMouse for Bluetooth. The best thing is, I don’t need to attach any dongles, and when I have everything paired, docking the netbook while working on a desk simply involves putting it down and connecting the external monitor. No USB cables to muck around with.

Bluetooth PAN is also great way to get wireless Internet tethering from my phone, and much more power efficient than using Wi-Fi tethering.

Getting the parts

The first step was to see what I needed to add Bluetooth to the netbook. HP’s specifications say Bluetooth v2.0 was indeed an option for this particular netbook. So it means all I needed to do was find the Bluetooth module’s part number, order it and install it. I love it when PC manufacturers publish the maintenance and service guides for the laptops, because it just makes life much easier to perform DIY post-warranty service.

To my horror, ordering HP’s official Bluetooth module costs an arm and a leg, and it doesn’t even include the connection cable between the system board and the module! So I looked for alternatives on eBay.

It was soon obvious that there are overwhelmingly many different Bluetooth modules for laptops. In general, manufacturers design their computers so that the parts are interchangeable between devices. So I searched for "HP Bluetooth Module" and went through the list. Eventually I found a listing for Broadcom BCM2046 Bluetooth 2.1 module plus the cable for roughly AUD$20. Sweet! What’s more, the listing claims that this part was compatible with the HP Mini 2133 and 2140 netbooks. The fact that it also came with 4 screws was rather curious, because the HP Mini 2140 only uses double-sided adhesives to attach the module.

Anyhow, I was willing to give that a try. The most important thing is that the module was compatible (that I didn’t know in advance; it just should work and looks about right), and that the cable had the correct adapters (I had to take the eBay seller’s word for it).

Installing the module

Receiving the goods after about a week and a half, it was time to perform the surgery and disassemble the netbook. First the keyboard came off, exposing the hard drive and the DDR2 memory.

Unfortunately for the HP Mini 2140, the Bluetooth module was located under the palmrest and left of the touchpad. So it’ll take a little more effort to access it. It turns out that even though my netbook didn’t come with Bluetooth, the double-sided adhesive that holds the Bluetooth module in place actually came with the system board. Excellent. That makes my job so much easier.

Final thoughts

For for a mere $20, my little HP Mini-Note 2140 netbook now has Bluetooth! What’s more, the particular module that I bought was Broadcom BCM2046, which is Bluetooth v2.1. Had I gone with official HP parts, not only would it have costed me more than 5x more money, it was only Bluetooth 2.0. Not that there’s very much difference, but 2.1 is meant to give higher data rates and use less power.

A feature of this course is that it is heavily industry-focused, and every week, we have successful real-world entrepreneurs (not just a lecturer) as guest speakers to share their experience and expertise.

Ask TVC is a site our group have launched to share this exclusive opportunity with the world. If you are running a business, or thinking about getting into the game, then fire your questions away. We’ll gather the top rated questions for each speaker and we’ll post the answers after the lecture.

The answers to Tjoos.com (Kim Chen and Bart Jallema) questions are now posted, and we still have Viocorp (Ian Gardiner), Omnisio (now YouTube; Ryan Junee), Atlassian (Mike Cannon-Brookes), and many more to come!

So check us out at asktvc.nfshost.com and let us know what you think.

However, there was a bit of drama behind why I made the change – unfortunate, but a valuable experience indeed. My website was hacked.

On 3 Aug 10 at 1532h, I received a notification email from my blog telling me that a password reset via forgotten password function has been actioned successfully. Knowing that I am the only registered blog user, this was one of two scenarios: either it was a hoax email, or my blog had been compromised (I’ve blurred the name of the hacker who claimed to be responsible, to protect his/her identity):

By the time I read the email, I was on my way home from uni, so the only thing I could do was to assess the situation to find out what has happened. Loading up my website from my phone, it was very clear that my website had been compromised. The immediate action for this security breach was to shut it down completely, but unfortunately I didn’t have access to my web host password then. It’ll have to wait until I get home. I seems that it was a website defacing attack, hopefully with minimal damage.

So, by 1730h, I’ve suspended the entire website first to stop the defacement from being accessible by the public, and then I proceeded to assess the damage. The database content was intact, WordPress itself was intact and functional, and the only damage I could find was to the WordPress theme. That black page really does not look like Sadish’s MistyLook theme. I’ve established what I needed to do fix the damages and recover from this incident. While I’m at it, why not choose a new theme for a makeover!

At 1945h, I reactivated my website, regained control over my WordPress account, but restricted it so no one else has access to the site while it was staging. By 2400h, and after a period of testing, my blog was good to go again. With a brand new theme to replace one that was hacked.

Now, what I still don’t understand is, how was it possible that my account email address was changed (so password reset could succeed). Was it through some kind of SQL injection? Have you had a similar experience, and what did you do?

All that I’m worrying about now is whether or not a backdoor was left somewhere I couldn’t find… Without knowing the mechanism of entry, how do I take steps to ensure that it doesn’t get exploited the same way again?

pv can be found at http://pv.codeplex.com/, and should work for you if you have a Carbon Management Solutions CMS-2000 or Schneider Electric SunEzy 600E (judging from a sample protocol exchange).

I’ll have to give full credit to the folks at http://www.solarfreaks.com/cms2000-inverter-rs232-serial-port-hack-cms-2000-rs232-t271.html who did the initial work on reverse engineering the communication protocols. Building on what has already been done on working out the protocol, and doing a bit of reverse engineering myself, the library supports sending arbitrary data frames for further exploring, as well as the known protocols.

JinbaIttai wrote a Perl script to poll the inverter, but unfortunately I don’t particular like Perl. So, I decided to write my own in my language of choice – Python. Also, a word of thanks to Ingmar for providing a sample of the protocol for the SunEzy 600E.

There are still quite a number of data fields that remains a mystery – getting a hold of the protocol from the CMS-10000 would really, really help.

Here’s a list of the features in the library:

• Craft custom frames to be sent to the serial port
• Reads inverter parameters and status information
• Verifies checksum for received frames
• Enumerates all known messages for quick reference

The module comes with a working example. Just run the package like so:

The code for this sample can be found in __main__.py.