My solution for ADSL frequent dropped connections

Some time ago I had problems with my ADSL connection. It was stable when my "speed" was limited by the provider to 2 Mbps. After a service upgrade I had frequent dropped connections particularly in the evenings. With the new service upgrade the "speed" was limited only by the characteristics of my phone line (around to 6 Mbps at that time).

This post describes the solution that I found to reduce  the number of connections dropouts due to the modem sync loss.

I checked through my modem that the SNR (ration signal/noise) decreased considerably throughout the day, starting around 6 dB in the morning, 3 dB at afternoon, 0 dB at end of the day and consequently a loss of synchronization.

I thought that if I could increase the SNR via a connection "speed" reduction then I can improve the situation. As my modem does not allow the parameterization of the maximum "speed" I tried to reduce my "speed" through an external circuit.

The trick is to "mislead" the modem making it "think" that my phone line is worse than it really is. Once the modem is synchronized, I can put the phone line back to the "normal" state. In this way I could reduce my speed to about 5 Mbps and have a SNR around 9 dB in the morning and keep a SNR around 3 dB at night that gives some margin to avoid dropouts.

The working principle of the used circuit is the following:

When the modem is powered ON with the switch "S1" in the open position, the modem will be connected to phone line with the inductor "L1" connected in series. This inductor causes the modem to synchronize at a lower "speed" (compared with the phone line without the circuit). It reduces the bandwidth of the phone line and consequently the synchronization "speed".  At this stage the synchronization "speed" of my modem is approximately 5 Mbps and the SNR around 6 dB.

When the modem is already synchronized then we close the switch S1. This switch "eliminates" the inductor "L1" from the circuit and put back the phone line to its normal state. At this stage the synchronization "speed" of my modem is approximately 5 Mbps (as before) but the SNR is around 9 dB.

When we close the switch "S1" and if the "L1" inductance is relatively high, the transition will be "abrupt" for the modem and we will have a synchronization loss. To make this transition more smooth I used the following circuit:

L1 = 2 uH

L2 = 2 uH

Note: The inductance values are approximate and obtained experimentally for my environment. If you want to try this circuit please check what is the best values of inductance for your environment (modem and phone line). You can start with a high inductance value and after removes turn by turn of the coil.

I added the switch "S3". It allows disconnect/connect the phone line instead of the modem power.

The operation sequence is the following:

1 - All switches OFF

The modem is disconnected from the phone line. We have a connection loss.

2 - S3 ON

Wait for the modem synchronization.

3 - S1 ON

The inductor "L1" is "eliminated" from the circuit.

4 - S2 ON

The inductor "L2" is "eliminated" from the circuit. The sequence is finished.

We need to repeat this process whenever the modem is restarted (for example, after a power failure).

The prototype of the circuit was built with material that already had at home.

Conclusion

With this circuit I reduced the number of dropouts from around 3 to 5 by day to about 1 or 2 per week. Currently I have another provider that uses better lines/equipment and my connection is stable at 7 Mbps without the use of my external circuit.

Cooler Master Silencio 550 thermal review

After reading some articles about the computer case Cooler Master Silencio 550 I finished with doubts about its thermal performance and if it was ok to my use (I do not intend to make use of “overclocking”).

One of the best articles that I found was the following one from CCReviews: CCReviews

However habitually in the reviews there are 2 missing important values to be able to compare the performances of a computer case: 

• The temperature rise inside the case (from ambient temperature)
• The computer power consumption

I explain:

The computer electric circuits "waste" power inside the box that will heat the computer case. From the air inlet openings and correspondent fan we have air going inside the case at ambient temperature. This inlet air will be heated inside the computer case. For the same cooling (fans/airflow) more power dissipated inside the case gives higher temperature rise (in relation to the ambient temperature).

The computer consumption is an useful information to compare with other computer configurations . We can estimate the power dissipated inside the computer case from the power consumption. As today the efficiency of the power supply is quit high (>95%), the power dissipation is only a little bit less than the computer consumption.

The dissipated power inside the box is a function of the computer configuration (motherboard, CPU, graphic card, etc..) and its use (games, internet, office, etc.).

For example, for the same dissipated power, if inside the case we reach a temperature of 50ºC with an ambient temperature of 20ºC it will approximately reach 60ºC with an ambient temperature of 30ºC and 40ºC with an ambient temperature of 10ºC. This is why the temperature rise information and the power consumption is important to know.

The temperature of the CPU is function of the temperature inside the computer case,  the type of the CPU fan and the CPU use.

My thermal performance test

I used the following configuration to made a thermal performance test with my computer case Cooler Master Silencio 550:

- Used material: See my preview post

- Computer case fans: Original fans (2 fans 800 rpm)

- CPU fan: Original fan supplied with the CPU.

- Computer case without the "removable drive bay" (see below)

- Use: Running DiRT 3 game

To improve the air flow I removed the “removable drive bay”. The "removable drive bay" is located in front of air inlet fan that doesn't help with the air flow inside the computer case. For my use the remaining expansion capacity of computer case is more than enough.

To measure the ambient temperature I used an external equipment (my multimeter). My multimeter uses a thermocouple sensor to do temperature measurements (with a good precision).  This temperature sensor was placed close to the CPU (see photo below)

To measure the power consumption I used an energy meter.

I got the following results:

Average consumed power: 193W (212W max)

Computer case temperature rise (from ambient temperature): 17ºC

CPU case temperature rise (from ambient temperature): 29ºC

The CPU is specified for a maximum case temperature of 72.6ºC (see ark.intel)

In this conditions I can play DiRT 3 (or a similar game) with an ambient temperature around 43ºC ..!

Note: This analysis is concerning only the CPU temperature.

Conclusion

The thermal performances of the box are not fantastic but considering the low level of noise, the construction quality and the price, the result is very good. It allows a comfortable use of the computer* without a risk of CPU overheating.

* With the used configuration (see my previous post) and without overclocking

Complementary information

The box has one edge used to separate the cabling areas. I arranged the cables without passing over it.

To connect the USB 3.0 front panel connector without using one of motherboard external USB connectors I used a USB 20 pin to 2-port USB 3.0 adapter (see below)

Assembly my computer

I use a desktop computer and a laptop. My preferred computer to work is the desktop that I use together with two monitors.

My desktop computer began to be very limited and without no major expansion possibilities (ISA interface instead of SATA). I decided this year to purchase a new computer.

So far my computers were assembled by specialist manufacturers. After a market search I didn't found a computer that corresponds to my specification and I decided to assembly my computer.

Even if the characteristics given by computer manufacturers seems "fantastic" the reality is different. Below you have some of the limitations that I found (in Mars 2012):

• No USB 3.0 or USB 3.0 not available on front panel 
• Hard disk SATA II instead of SATA III 
• SSD disk with low capacity (68 GB or less) 
• 4GB of memory and expansion limitations 
• Small computer case and expansion limitations 
• Graphics card with low performances (compared with other not so expensive cards) 
• Noisy computer 
• Missing drivers, manuals and technical information 
• CPU outdated

To compare graphics cards and CPUs I recommend the following sites:

CPU: http://www.cpubenchmark.net/

Graphic card: http://www.videocardbenchmark.net/

After searching and compare quality/performance/price I used the following material:

• Computer case (power supply included): Coolermaster SILENCIO with GX 550 certified
• Motherboard: Gigabyte - GA-Z68X-UD3P-B3 - ATX - Intel Z68 - 1155 Socket (Rev 1.0)
• CPU: Intel Core i5 2500K / 3,3 GHz - LGA1155 Socket - L3 6 MB - Box
• Graphic card: Sapphire - Radeon HD 6850 - PCI Express 2.0 x16 - 1GB
• SSD Disk 128GB: Crucial - M4 - 2,5" - SATA III
• Hard disk 1TB: Western Digital - Caviar Black - 3,5" - SATA III
• RAM memory: Corsair - CMZ8GX3M2A1600C9  - DDR3 1600 - 8 GB COR CL9
• DVD Burner: LG - GH22NS50 - 5,25" - SATA
• USB 20 pin adapter to 2-port USB 3.0: Lian Li UC-01

The USB 20 pin adapter to 2-port USB 3.0 is used to connect directly the computer case front panel USB 3.0 plug (standard model) to the motherboard USB 3.0 20 pins connector.

Computer layout after assembled

I ordered all the material via internet and got all stuff in a week. The fastest delivery was the computer case (ordered on a Sunday and received Tuesday).

The Intel i5 CPU is already delivered in a box with a fan and a manual with the assembly instructions. It is not necessary to apply thermal paste as it comes already with a thermal conductive pad.

I received a computer case with a 650W power supply but I ordered a computer case announced with a 550W power supply.

As bonus, with the graphics card I also received a code to be able to download the game Dirt3 for free.

The major risk when you mount your computer is when you do not have another compatible  computer to test the parts separately (which was my case). If for example there is a problem in the CPU or mother board will be difficult to know which one is the "guilty."

The most sensitive part (but is not complicated) is the assembly of the CPU. You have to be careful with static electricity that can damage the CPU or the mother board. In my case I did the assembly barefooted, and touching regularly on a tap to discharge static electricity to the earth.

After it was only assemble the parts and connect/route the cables. There is no big possibility to connect wrongly a power supply plug in the motherboard because each plug can only enter in their correct position and location. Sometimes you need to put together two power supply plugs on the same motherboard connector, which was the case for the ATX_12V_2X4 and ATX connectors of my mother board.

Where I spent more time was to routing and fix the wiring to minimize the "spaghetti" appearance.

When everything was assembled, the crucial moment arrived ... I turned ON the computer and ... the CPU fan and BIOS worked :)

As operating system I installed the Windows 7 Ultimate 64-bit version. In the SSD I put all the main software and in the hard disk I put the data (photos, videos, documents, etc..) and the no important software.

An important point for anyone who uses a SSD drive is not to make and allow disk defragmentation. SSD uses flash memory, defragmentation not improve disk performance and contributes to reduce its lifetime because it increases the number of times of data written in the same memory location.

The results obtained with my computer are the following:

Windows 7 performance index (scale 1.0 to 7.9)

Computer boot time after first installation (with only a few start-up processes):

Bios boot time: 16 seconds
Windows 7 boot time (*): 21 seconds
Total: 37 seconds

Computer boot time after some months (with more start-up processes):

Bios boot time: 16 seconds
Windows 7 boot time (*): 33 seconds
Total: 49 seconds

 (*): After finish "working in background" (mouse pointer with the normal shape).

Conclusion
The computer is very quiet and so far I'm pleased with their performances. The only element that is noisy is the 1TB hard disk.

The boot time is more or less the same that my Android tablet. Thanks to the SSD disk...!

Later I will publish a post with the performances and characteristics of the computer case Coolermaster SILENCIO.