Tag: Hardware

Maximizing the 32-bit 4GB RAM Limit

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If you have a 32-bit system with 4GB installed, you can reduce the amount of RAM that gets wasted and make some more of it available by opening the BIOS configuration and reducing the AGP aperture setting to the minimum amount (e.g., 4MB).

Note: this may affect 3D graphics performance, so it is best for systems which don’t do 3D gaming or systems with video-cards that have a lot of video memory.

 

Personal anecdote… ▼

Hotplugging SATA Drives

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The SATA specification allows for SATA drives to be hotpluggable.

This usually allows manufacturers to create external drives that can be hot-swapped (via USB) more easily than with IDE drives. However, this usually also works for internal drives.

If you have an internal SATA drive (hard-drive, DVD drive, etc.) which is not connected to the motherboard and boot up Windows, not surprisingly, it will not show up in the Device Manager. If you then connect the drive’s data cable to the motherboard (and perhaps optionally) do a re-scan in Device Manager, the drive will then show up because the SATA controller detected the drive and made it visible to Windows.

This is great. If you accidentally forget to connect a SATA drive to the system and don’t want to shut down or want to create your own sort of external drive, this feature is very helpful.

Unfortunately, like most things, the pros come with cons. In this case, while the newly connected drive becomes visible to Windows and is usable, it will likely have poor performance. Windows loads the drivers for the drive on boot, so if you connect the drive after booting, instead of loading the tuned, high-performance drivers for it, it will end up using simple, low-speed access to (i.e., it will not use UDMA). You can see this as extremely slow transfers to/from the drive. If you do this with a DVD burner for example, it will be limited to ~2x even if you set it burn at 8x or whatever). You can also see this effect in the Task Manager’s Performance tab; the CPU load will jump when you use the drive, but no processes will spike because the load is coming from the kernel. This may or may not also occur in Linux or Mac.

So while SATA allows hotplugging drives, it doesn’t mean it will work well. Manufacturers will still need to provide a shim to allow for maximum performance and OS developers will need to better detect newly attached SATA drives and load the drivers at runtime.

Bigger Hard-drive = More Fragile

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In one of his podcasts, Steve Gibson of GRC discussed how his program SpinRite works to attempt to recover data from defective hard-drives. He mentioned that modern drives are more susceptible to failures now due to higher data density and smaller bit sizes. This is correct, but some people don’t know what that means, so as always, an analogy is helpful.

Hard-drives store data as magnetic binary bits. As a simplification, lets say that when the drive head writes a 0, it aligns the magnetic bit to positive and to write a 1, it aligns it to negative. However, the magnetic bit isn’t a single atom. Like everything else, it is made up of lots and lots of atoms. Just like how a fridge magnet is made up of millions of tiny atoms, drive bits are made up of lots of atoms that align together to give it a specific magnetic polarity that the drive head can read and interpret as a 0 or a 1.

Now for simplicity, imagine we have an old hard-drive in which each bit on the drive platters is made up of 100 atoms. When you write data to it, the write head tries to align the 100 atoms in the bit to the same polarity (positive or negative). However, this will not always work correctly and some of the atoms may not get aligned correctly (or at all). That is, the bits are either positive or negative which correspond to either a 0 or a 1 (this is a simplification.

In our old, 100–atom/bit drive, if eight atoms are corrupt and incorrectly written, then 8% is bad and 92% is good, so when the head reads the magnetic polarity, it gets a nice, solid, clear reading.

Some time goes by and data sizes go up, so hard-drive manufacturers have to make the drives bigger, but they cannot increase the physical size of the drive. Packing in more bits into the same size means using smaller bits (i.e., higher data density).

Lets say we now have a fancy new drive that is 5x the size of the old one. Instead of using 100 atoms per bit, our new drive has only 20 atoms per bit. As a result, if eight atoms are incorrectly written, then instead of only 8% of the bit being corrupt, it is up to 40%. We still get more correct than incorrect at that rate, but the margin is much smaller (even worse if there are more than eight bad atoms).

Some more time goes by and we get a drive with 10x the size of the first drive (2x the previous one). Instead of 100, or even 20 atoms per bit, it is down to 10. Now when eight atoms are incorrect, it is 80% bad and only 20% good! That means the drive used to be very stable with eight bad atoms per bit, but is now completely unreadable.

The reliability of the drive went down as the data density went up because while there is more data per drive, there is less data per bit which makes it bigger, but less reliable and more prone to corruption and data loss.

Firmware Upgrade Safety

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Updating firmware is still often a somewhat risky task. The firmware is the software built into a chip in the hardware that provides the low-level functionality (drivers are the higher-level software that provides more advanced functionality).

The problem with updating firmware is that if the update does not go perfectly, this can leave the device in an indeterminate state without the ability to even try again since the low-level functionality is needed to upload firmware to the device in the first place.

In the old days, flashing a new BIOS or CD drive firmware was quite risky and resulting in much “bricking” (rendering a device useless). (Technically, there are usually ways to restore a working copy of the firmware like the manufacturer did in the first place, by cracking the device open and connecting to special ports on the motherboard (e.g., JTAG). Not surprisingly, manufacturers have tried coming up with better, safer solutions. Yet, updating firmware, especially with untested or third-party firmware remains risky to this day.

This is silly because there are numerous ways to prevent bricking devices.

One method that some manufacturers have implemented (usually on motherboards) is to use two BIOSes on the board. That way, if the main one fails, then the user can hold a special key combination or short a specific jumper or some such to restore a copy of the non-writable ROM backup to the erasable one.

This method is effective and can even be adapted in another way. Instead of having two copies of the firmware, simply have two flash drives. That way, when you upload a firmware, instead of being written to the main chip, it is saved to the storage chip, then if and only if it was successfully uploaded, it is quickly written (“flashed” if you will) to the main one. This way, the device can easily detect if the upload failed and provides an all-or-nothing flashing experience (an atomic transaction/operation in database parlance).

Laptop Screen Going Blank

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I was helping another person in the Windows newsgroup who was complaining that their laptop’s screen goes blank after 30-60 minutes and they have to open and close the lid and press the power button to get it back. My advice:

It could be caused by overheating, dust, or maybe a loose connection. Try holding the laptop up, with the display’s screen facing the ground. Gently shake it a bit and see if the screen goes blank. If it does, then that’s your problem; it’s not a laptop, it’s an Etch-a-Sketch.

Bad RAM? Maybe Not.

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It has become more and more popular to blame computer problems on bad RAM—poor RAM. While it’s certainly possible to have a RAM module with a problem, it’s not as common as people would have you believe. In the past few years with the release of various RAM testing apps, there has been a surge of comments to the effect of “test your memory”, “you’ve probably got bad RAM”, “you need to replace your RAM” in response to posts about computer problems. It is just so easy to blame the RAM since it’s one of the only things that can successfully explain intermittent or unexplainable problems. The snafu is that even when the RAM is at fault, it’s not necessarily because the RAM is bad, it could—and usually is—because the connection is bad.

There are three common ways that RAM can be the cause of a problem. The way that everyone is raving about is a defective RAM module, that is a problem in a RAM chip or circuitry. This would render it useless (for all intents and purposes) and require just chucking it and getting a new one. Another problem could be the contacts on the edge of the RAM module could be dirty or have a patina on them, which impedes contact with the socket. In this case, the RAM may or may not be detected and could work partially or not at all. Finally, the RAM socket itself could have a problem. It could be that the contacts are dirty or the pins/pads are bent. Fortunately the contact problems are more common and easily fixed.

If the contacts on the RAM module are dirty, then simply using a little water to dampen a small sponge can be used to clean them. There are fancy patina cleaners, but all you really need to do is to clean those little pins on the edge. Pretty much anything will do, even alcohol or solvents, as long as you don’t let them dissolve the metal, just clean them and wipe it off. The best solution of course is to use some good old soapy water and some toilet paper.

The RAM socket is a little more tricky. If the pins are dirty, an effective solution is to lightly wet a used toothbrush, and gently scrub the socket up and down with it. This will do a good job of cleaning it.

If the pins on the socket are bent, then it may not make proper contact with the RAM module and will be a problem. More often than not, you will have to abandon the socket or even the whole motherboard, but with a little dexterity and the right tools you can fix it. You will need a long, find-tipped object, like a dentist pick, or something. It must be long enough so that your hands don’t obstruct your view, and pointy enough so that you can work with the tiny pins. You will probably need two so that you can grasp them and bend them back. You will also need good lighting and perhaps a magnifying glass. Take a good look at the socket and locate the bent pin. Examine it carefully to determine exactly what the problem is and which way you need to bend it to fix it. Use the tools to carefully bend it back to match the others. Plug in the RAM and give it a test. Be aware however, that they are metal and can only be bent so many times before snapping.

In conclusion, don’t throw away your RAM just because someone told you that it’s the cause of a problem or because a testing app said there’s problem(s). Before heading to the store, clean the RAM edge and run it through the test app. If that doesn’t fix it, clean the socket. If that doesn’t fix it, check for bent pins. If that doesn’t fix it, then go to the store.

Quieter, Smoother Computer

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Most computers come with fans to keep them running cool enough to avoid problems. Unfortunately, fans have moving parts, move fast, and stir air. All this results in quite a bit of noise which can cause headaches, not to mention being down right annoying. It also causes a lot of vibration which further adds to the noise, headaches, and annoyance. Some people get rid of their fans and use alternative cooling methods, however most of these are just too expensive for the regular computer user, and worse, too complicated. Good computer cases will come with rubber feet instead of the hard plastic ones that cheaper cases have. The rubber feet will absorb the vibrations instead of passing them to the desk, floor, or whatever surface the computer rests on. If your case does not have rubber feet, then you can add them if you are comfortable/able to open the case. If not (or even if your case does have rubber feet), there is a quick, easy, and cheap trick that can help to reduce vibration which will result in less noise and provide quieter, smoother computing environment.

Simply place a couple of foam-rubber mouse-pads beneath the computer. You’ve probably got a few lying around somewhere, or can easily buy a couple for under a dollar. The design does not matter, so you can get generic ones for less. The thick, foam-rubber kind work best, although even the thin rubber kinds are better than nothing. In either case, you just slip in under the computer to cushion it from the desk, making sure that the rubber side faces the computer. Even better, fold it in half (rubber side out), and you’ve got a vibration damping, noise canceling, double-cushioned, non-slip shim between the computer and the desk.

*UPDATE*
Here is a blog entry which says pretty much the same thing and includes pictures.

Tip: Smooth Mouse Scroll Wheel

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Here’s a tip for those with scroll mice. Take the clicker out of the wheel. Scroll mice usually accomplish the clicking of the scroll wheel by means of a spring or metal stick that press inside the wheel. Take this out, the wheel will turn nice and smooth. It may take a little getting used to, but it will soon feel great.

Of course you should realize that the clicking serves a function: to limit the movement of the wheel. If the scroll wheel is too loose, it may spin out of control without it, but normally it won’t. In fact, in some mice, the clicker may cause unwanted scrolling, so removing the clicker will eliminated that.

(The little metal stick inside my mouse broke recently, and I panicked because it was a fairly new, expensive mouse, but before I knew it I was hooked—pun intended. I never want to use a clicker again.)

Clean and Oil Those Fans

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Computers are not invulnerable to dust. They have a tendancy to get clogged up with plenty of dust which at best causes overheating. It is a good idea to regularly clean out all the dust in a system to keep it as cool as possible since dust is an insulator. Removing the dust will allow better airflow, especially through fins on heatsinks and lighten fan blades, allowing them to turn faster.

Another tip to keeping a computer running in peak condition is to oil fans. Anything that moves should be well lubricated to allow it to do so smoothly and fans are no exception. Every once in a while (at least once a year, depending on how dusty your environment is) you should remove the fans in your system, take them apart, and oil them.

To oil a fan, you need to disassemble it. This is the tricky part. To disassemble a fan, you need to remove any stickers that cover the capstan. Next, remove the washer that holds the capstan. You will need a pointy knife or something to do this. Usually they will be made of plastic, but sometimes metal. They will almost always be a small flat disc with a hole in the middle and have a cut (think of a “C” where the ends meet but do not attach). Once this is off, you can remove the fan blade assembly. Before oiling it, you should thouroughly clean it. All kinds of grime and grit can get in there and cause it to make noise, as well as slow it down and create friction heat. Once you’ve cleaned it, then you can oil it. The type of oil does not matter too much depending on the fan. Most fans are cheap anyway so you do not need to shell out for top of the line lubricant. Even vegitable oil is better than nothing in a pinch. Synthetic teflon lubricant can be found in any bicycle shop and works great. You should oil the parts that touch and move. This includes the capstan, and the hole in which it goes. You will also want to oil the joint where the capstan attaches to the blade hub and where the blade hub rests on the washer. Do not over-oil since that will just make a mess with no extra benefit. In fact you should probably clean up any excess before putting it back. Put the blade assembly back into the fan and give it a test spin. Make sure that it is running smoothly. Now place the holding washer back on the end of the capstan and finally the sticker. Put the fan back, plug it in, power it up, and watch it spin. You may want to consider comparing fan rotation speeds before and after. Also, make sure to notice the noise level after oiling.