Aleksandar's computer workshop

Let's see what Aleksandar was fixing today.
My findings, tips & tricks related to computers, internet, programming and other stuff I was working with.

Monitor Display Turns Sideways or Upside Down

"Dad, there’s something wrong with the computer!"

If you ever pressed Ctrl-Alt-Right it could happen that your screen got rotated.

The Ctrl-Alt-Direction key sequence is supposed to be used for changing your workspace.
On my computer at work it changes the screen orientation.
Ctrl-Alt-Up - right side up
Ctrl-Alt-Right - 90 degrees
Ctrl-Alt-Down - 180 degrees
Ctrl-Alt-Left - 270 degrees(If that doesn’t work, try Ctrl-Shift-R)
Looks like ATI & Intel copied the keystroke for the same “feature” in their video card drivers.

To fix the issue press Ctrl-Alt-Up. To permanently fix the problem go to:
Start >> Control Panel >> Display >> Settings >> Advanced
Where it is after that it dependent upon your video card. Look for hot key section.

Windows Vista Battery Saver

Some rumors are saying that AERO interface is draining the laptop battery due to intensive GPU usage.
 
There is small utility which "optimizes" the Vista options. Does it really works on your laptop you have to test yourself.
Here are few articles related to this issue:

Why 99% of Power Supply Reviews Are Wrong

http://www.hardwaresecrets.com/article/410

http://forums.hardwaresecrets.com/why-99-power/1937
http://forums.hardwaresecrets.com/why-99-power/1937/2



1. The use of a multimeter is a declaration that the person has no idea of what they are dealing with. Multimeters sample at their designed rate and display an average which completely masks the underlying reality of wildly shifting loads. (If this were not the case, multimeters would have a blur for their least significant digits.)
2. Voltage is EVERYTHING. The current don't flow 'til the voltage says go. Current is merely the result of a voltage differential and is limited by the resistance to it.
3. The 'resistance' (readers please note the quotes before madly posting that there is more than simple dc resistance in play) presented to each rail of the PSU is a maelstrom of shifting values. One moment just a tad, at another, a gargantuan jump. It is to this nightmare that the PSU must react. Testing with static loads is a joke.
4. The specs for PSUs are NOT expressed as 'averages' - if your voltages show a sag, you're 'near the edge', if not 'in deep doodoo'! If the voltage(s) spike/sag outside the limits, ALL BETS ARE OFF.
5. PSUs are mostly 'snake oil' - sold to the indifferent and the gullible (not to mention the adamantly ignorant). I remain convinced that a 'cheap' PSU costs $2.95 to manufacture while a 'quality' unit costs $4.95; the rest is packaging, transportation, advertising and mark-up, mark-up and more mark-up.
6. The 'rating' of a PSU is pretty well WHATEVER the vendor wants it to be; they're the ones who set the parameters for the derivation. (I remember some 30-odd years ago reading an article showing how a stereo amplifier that had true specs of 5W/channel, 20-20K +/- 0.5%, THD/IMD under 1.0% could be advertised as a 200W/channel unit - LEGALLY!) The soul bragging about his 650W Q-Tec has yet to discover that it is 'rated' in peak (transient) power, not continuous (where it would be lucky to hit 425W) and that that particular brand has garnered such a bad rep that it has been abandoned.
7. PSUs are made with 'industrial' grade components (+/- 20%). The actual capacity of an assembled unit will fall in a classic bell-shaped pattern. The bean-counters are the ones who decide the 'most profitable point' between 'returns' and 'reputation'. (Anyone still believe ANTECs are 'built like tanks'? There was a time...)
8. The 'average' system draws less than 200W from the wall socket. Those who cannot grasp the difference between 'average' at the wall and instantaneous 'peak' (all rails SIMULTANEOUSLY) at the PSU output will continue to live on their 'luck of the draw', convinced that a 450W unit can run anything.
I doubt I will ever see a PSU evaluation that actually 'tests' the PSU's ability to maintain voltages within spec (down to the microsecond, or at least millisecond) while each rail was being jumped (both up and down) by 1,2,3...max amps from each possible point (1, 2, 3...max amps), SIMULTANEOUSLY at RANDOM rates. But then, I doubt there is a PSU that could pass.
And considering that component manufacturers are no more forthcoming in their actual peak demands, it probably doesn't matter.
Caveat emptor.

How to wire Ethernet Cables also known as UTP CAT5 patch cables

Every so often I come across a cable only running in half duplex with severe packet loss, only to find out it was incorrectly wired. In 1991 EIA/TIA released their joint 568 Commercial Building Wiring Standard. These standards help reduce electro-magnetic interference to ensure rated cable speeds.

About the Cable

You can find bulk supplies of the cable at many computer stores or most electrical or home centers. You want UTP (Unshielded Twisted Pair) Category 5 cable for basic 10/100 functionality. You need CAT 5e for gigabit (1000BaseT) operation and CAT 6 gives you a measure of future proofing. Bulk cable comes in many types, there are 2 basic categories, solid and braided cable. Braided cable tends to work better in "patch" applications for desktop use. It is more flexible and resiliant than solid cable and easier to work with, but really meant for shorter lengths. Solid cable is meant for longer runs in a fixed position. Plenum rated cable should/must be used whenever the cable travels through an air circulation space. For example, above a false celing or below a raised floor. 


CAT5 Cable internal structure

Inside the cable, there are 8 color coded wires. These wires are twisted into 4 pairs of wires, each pair has a common color theme. One wire in the pair being a solid or primarily solid colored wire and the other being a primarily white wire with a colored stripe (Sometimes cable doesn't have any color on the striped cable, the only way to tell is to check which other wire it is twisted around). The twists are extremely important. They are there to counteract noise and interference. It is important to wire according to a standard to get proper performance from the cable. 

About the RJ45 Ends

The RJ45 end is a 8-position modular connector that looks like a large phone plug. There are a couple variations available. The primary variation you need to pay attention to is whether the connector is intended for braided or solid wire. For braided/stranded wires, the connector has contacts that actually pierce the wire. For solid wires, the connector has fingers which pierce the insulation and make contact with the wire by grasping it from both sides. The connector is the weak point in an ethernet cable, choosing the wrong one will often cause grief later. If you just walk into a computer store, it's nearly impossible to tell what type of connector it is.

 
RJ45 Plugs


About the cable types

There are 3 main types of RJ-45 cables that you will run across in networking, both LAN and WAN. Some interfaces can cross and un-cross a cable automatically as needed. The TIA/EIA-568-A specifies two wiring standards for a 8-position modular connector such as RJ45. The two wiring standards, T568A and T568B vary only in the arrangement of the colored pairs. Your choice might be determined by the need to match existing wiring, jacks or personal preference, but you should maintain consistancy. 
  • Straight-through or standard patch cable, the colored wires are in the same sequence at both ends of the cable, which is used to connect to a hub or switch.
  • Crossover or cross-connect cable, the first (far left) colored wire at one end of the cable is the third colored wire at the other end of the cable, used to operate in a peer-to-peer fashion without a hub/switch.
  • Rolled, Rollover or Console cable, the colored wires at one end of the cable are in the reverse sequence of the colored wires at the other end of the cable. Mostly used to configure routers via console.

T568B CAT5 Specification and RJ45 Plug pin numbering

 

Different EIA/TIA-568 wiring specifications

 

Sample of prepared plugs as standard patch cable 

 

RJ45 Crimping tool

 

 

 

 

Video: How to make a Cat5e Network Cable