I am not sure I like this 'soft' power system. I suppose it's nice (at first) that the computer can turn itself 'off' when you choose 'Shutdown' from Windows and can optionally switch on at the touch of a key (Just like my old MacintoshIIci). But that also means (as with the Mac) that a cat walking across the keyboard could turn the computer on! It also means that it is all too easy to open the computer and insert expansion cards without realising the power was still on. To make sure the computer is really off, you need to switch it off at the back, if a power switch is provided there. On some ATX cases, but far too few, the main switch is on the front. On others, there is no main power switch at all and you have to unplug the power cord if you want to ensure the computer is really off.

Finally, I hope it does not cause you too much grief, but buying the 'cheapest possible ATX case' is not always a good idea. Cheap cases contain really cheap power supply units and these often lack adequate filtering, so (like cheap memory) they can be the hidden cause of all kinds of obscure problems. Admittedly, without a background in electronics and an oscilloscope, it is hard to tell a badly made power supply unit from a good one but, like anything else, the cheapest unit is not likely to be the best! For the sake of ten quid, I'd go for a well-known brand.

While all Pentium II processors use a 100MHz bus speed for 350MHz or faster, for a long time Intel marketed the Celeron as a 66MHz part only with 400MHz (6x66) as the maximum official speed. A visit to any 'overclocking' Web site will soon show you that a Celeron can often run much faster than this, but only by changing the front side bus speed on the motherboard.

I also would not advise using a processor faster than H-P recommends. Components such as voltage regulators may only be sized to suit the recommended processor speeds, or the hardware needed to increase bus speed to 100MHz might be missing. Since the motherboard specifications could also differ in various other ways, it would be dangerous to use an Asus Bios update that was not specifically for the H-P version. Using a faster bus speed probably also requires replacing your memory with PC100 specification modules and adjusting the speed of the PCI bus (set to half bus speed on a 66MHz board, but one third at 100MHz). The motherboard is a standard micro ATX form factor board, using the now standard 'PC98' specification for port colours and positioning. Therefore, it should be easy to get a replacement motherboard to fit your case.

I would not recommend it, however, unless you are running extremely processor-intensive software. An increase from 366MHz to 500MHz even if you increased bus speed to 100MHz would hardly be noticeable. To be worthwhile you need to at least double your CPU speed. It would also be a relatively costly upgrade - apart from a new processor and motherboard, you'd need to replace all your memory with PC100 compatible components. It would be far better to add a faster hard drive or more memory, then wait until 800MHz Athlons are available at bargain prices.

Your choices are either to make Insight replace the board (mutter about misrepresentation and Trade Descriptions Act) or run it at a speed that it will be happy with. Other people have found 4x83 or 5x75 to work.

That being so, the most successful dealers will be the ones who add some profitable service, such as selling integrated vertical application software. Other dealers become desperate to keep their business afloat and try to cover their costs by dabbling in illegal activities, whether it is including unlicensed copies of Windows and Microsoft Office with every computer sold, or selling pornographic CDs from under the counter. All too often I have seen businesses surviving for years when you wonder how they can make a profit, then one day the police raid the place and it is revealed that the business was a front for drug dealing or other illegal activity.

My reports last month referred to one model out of many different motherboards made by the PC Chips group. Other boards, despite very similar names on the chipset, use different chipsets and don't suffer from the problems we described. The problem is only with the model M590 board, which uses a SiS 5591 chipset. This board is no longer in production, though some may still be in the shops, its replacement models -the M585LMR is based on the VIA MVP4 chipset, while the M599LMR uses an SiS chipset but the later, and far superior, SiS 530. While PC Chips motherboards, like many other far-eastern products, never carry the maker's name, if your motherboard has a chipset named with some variant of the names VX Pro, TX Pro, PC 100 Pro, BX Pro, BXcel or several other variants (including one reportedly labelled as VIAgra!), it was made by the PC Chips group. You can identify the real chipset used either with utilities such as Sandra or ctPCI, or from the Bios identification string shown on boot -up. The M590 has an AMI Bios (if your board uses an Award Bios, it uses a different chipset) and the M590 Bios identification string will be something like:

51-0814-001437-00101111-071595570-001_10_CHIPSET-H

It is common for problems -badly soldered joints, connectors that don't make good contact, faulty capacitors -to resolve themselves as the system warms up. Computer technicians often use a can of compressed refrigerant to squirt at the board -the evaporation cools the component or joint and can trigger the symptom when you spray the faulty component. Apart from that the only solution is to swap components until the cause is found. I am going to make a guess, though, that the fault will turn out to be a badly made connection somewhere. Check power supply connections, memory modules (clean the contacts and look for bent spring contacts) or AGP and PCI connectors.

Of course, you may not want the update after all. It does nothing to fix the inherent problems with this motherboard, and there have been many reports of it causing new problems.

First, be careful to distinguish between sensors for CPU surface temperature and those for temperatures inside the case. In general, case temperatures can run around 10° higher than room temperatures and the designers of good quality systems usually specify a maximum operating ambient (room) temperature of 35° -not a limit that is likely to be a problem in Britain, except perhaps in the kitchen of a pizza restaurant.

Processor makers specify a maximum 'case' temperature for the processor -for AMD K6 chips, Pentium II and Pentium III chips this is either 70° or 75°C though, oddly, Celerons are expected to work up to 85°. By case temperature chip-makers mean the temperature of the ceramic material the processor is encased in and not the temperature inside the computers case. This should be measured at top-centre of the chip packaging (or for a PII or PIlI at the heat sink) but to do that on socketed processors would require drilling a hole in the heat sink and fixing a sensor into it. In practice, motherboards for socketed chips such as the AMD K6 family place a sensor in the centre of the socket underneath the processor. This won't get quite as hot. The Intel Pentium II and III has a built-in thermal sensor, which will measure higher temperatures since it is closer to where the heat is generated. For a PIII/450 with SECC2 packaging, the cover temperature has a maximum value of 75°C but the 'Tjunction' maximum, as measured by the internal thermal diode, has a 90°C maximum, and the L2 cache module has a 'T -Case' limit of 105°C. According to the Intel datasheets. CPU core temperatures can be up to almost 5°C higher. The 90°C limit is for the 450MHz version -faster processors usually have lower maximum limits. typically 80° or 82°C.

If a processor is running hot it may not be the fan that is at fault but the thermal contact between heat sink and processor. While the retail-boxed processors have heat sinks designed and attached by the maker, unboxed OEM versions will vary in quality. Often, badly-put-together systems will leave small air pockets under the heat sink. Since air is a good insulator -provided it is trapped -this severely affects heat sink performance. Some kind of thermal grease is needed to maintain a good contact. No matter how good the CPU fan is, it won't be effective if it is sucking in hot air -both AMD and Intel specify that the temperature of the air the fan is drawing over the processor should not exceed 45°C. Unfortunately, many computer systems are not designed as a whole but simply thrown together and many case designs do not have efficient cooling.

The built-in motherboard and CPU sensors may not be functioning correctly. These thermistors are cheap components, so those skilled in electronics may opt to try replacing them. Because of the importance of cooling, I have added a cheap digital wall thermometer to my troubleshooting toolkit. This is an indoor/outdoor model with the 'outdoor' sensor on a long wire. I replaced part of the wire to the sensor with thin wire from an old electric motor armature -this is heat resistant and thin enough to fit between the processor and its socket, allowing me to measure temperatures onboard without built-in sensors.

The thermometer is more useful, though, in measuring the temperature inside the system box and hard drive temperatures. Tucking it between the drive casing and its controller board, I have found that hard drives can start misbehaving when run at a measured temperature above 45°C. At that point the temperature in other parts of the hard drive is probably exceeding the 50°C maximum specified by many hard drive makers. I bought mine in the USA for just $15 at a Radio Shack store but Tandy and many other outlets have similar models available (check the maximum temperature they will measure though).

As PC Chips sell cheap motherboards, chipsets are chosen with cost in mind rather than performance. So they are not going to be the best-performing chipsets. For example, the integrated display adaptor will typically steal some of the main memory instead of using faster dedicated memory connected directly to the display chip. Partly because of this and partly because they don't spend time tweaking Bios parameters, the performance of PC Chips motherboards may be 1 0 to 20 percent slower than better-quality boards with the same processor. If you are just putting together a cheap computer this may be OK; even the slowest processors available can be much faster than you need them to be.

PC Chips makes a vast array of different motherboards, some much better than others. The only fairly common feature is the strange PC Chips habit of inventing new names for the chipsets used. Our past criticisms were aimed particularly at one model, the M590, manufactured at a time when there was high demand for 1 00MHz Bus speeds but few suitable chipsets available. This board (like PC Chips' M571 board, which ran at 83MHz) used a chipset made by SiS, designed for use only at 83MHz. However the M590 ran it at 90MHz and then programmed the Bios to lie about its speed and report processor speeds equivalent to a 100MHz-bus speed. We were concerned mainly about the deception, but also that many of these boards were unstable running at that speed, thus causing lots of crashes. At 66 or 75MHz they usually run fine.

My personal feeling is that I cannot feel confident in any PC Chips board, as I have seen too many of them cause problems. If a computer keeps freezing up it is very hard for the user (or even the professional technician) to know whether it is caused by software, bad memory, faulty power supply, motherboard or Bios bugs. So it can be very time consuming to identify the problem; it is much cheaper for the professional repairman or dealer to buy a new board.

When you take the cost of warranty repairs and support costs into account, these boards suddenly don't seem that cheap. We all know that selling PCs is a business where many firms fail. This is often because they have underestimated warranty repair costs. Buy a cheap PC and not only do you get cheap components that are more likely to fail, but you often get a supplier who is not very happy to have to handle the resulting telephone support and warranty claims.

If, on the other hand, you are an impoverished student for whom time is cheap and money is in short supply, a used bargain may be just what you need. A friend of mine tried this, though. After buying six different used PC Chips boards from three different sources without finding a single one that worked reliably, he started to appreciate my point of view.

If you do decide to get a new motherboard, you will find that few have Simm sockets any more, for the simple reason that no one makes 100MHz Simms. Adding Simm sockets usually reduces the maximum number of Dimm sockets and complicates memory management with potential issues of mixing different types and speed of memory. While most computers claim they can set the speed of each memory bank independently, this is a common Bios issue. Mixing the 5-volt Simms and 3.3-volt Dimms can also be problematic on many motherboards.

The TMC board you mention does handle Simms as well as Dimms. With only 66MHz memory you obviously have to run the memory bus at 66MHz and set the processor speed multiplier higher to compensate. Even so, you are likely to have to settle for a slower-than-rated CPU speed (ie 66MHz x 4.5 = 300). Some chipsets also claim to allow the memory modules to run at AGP clock rather than processor clock speed. This sounds rather tricky to me though -another recipe for possible Bios problems.

All in all, I would prefer to see new memory in a new motherboard. On the other hand, adding more memory to your present board is also not a great idea, if you can't use it in the new one. There is no simple good way forward, except to wait until after Christmas, when I expect prices will fall dramatically.

You don’t have to change your motherboard in order to upgrade your graphics card, or your sound card for that matter, but you might prefer to do so. If you're happy with a PCI graphics card, (which usually offers lower performance than an AGP option) you'll need to disable the existing graphics card in both Bios, (maybe by activating a motherboard jumper - check the manual for this) and from your existing 'Device Manager profile (which lives under 'System' in the Control Panel), install the new PCI graphics card and connect up your monitor. Windows will then ignore the integrated graphics chip and only recognise the upgrade. A 16Mb Voodoo 3 card would probably be the best PCI option and would certainly outperform your integrated 8Mb chip.

This said, however, for maximum graphics capability you'll need a 32Mb AGP card; as your motherboard won't have an AGP slot you will need to upgrade the motherboard and also your sound card. If you do want the best AGP card available and are prepared to upgrade your motherboard, then a GeForce-based graphics card is probably the most capable 3D option on the market, but if you're not prepared to cough up almost £200 - a 32Mb TNT2-based card, costing around £110, would probably be the best bet. As for sound card and motherboard recommendations, you don't mention having any specific requirements for the former, so a basic PCI Soundblaster card would probably suffice and when it comes to the motherboard (into which we assume you'll be putting the existing Pentium II 400) - so long as you opt for one with a BX chipset operating at 100MHz you can't go far wrong (given last month's lead Newsfile story, however, a PC Chips board would probably be best avoided).

The best processor options on a Socket 7 board are AMD's K6-2, or better still K6-3 which would cost between £35 for a K6-2 400 and £l00 for a K6-3 450. If you can afford a K6-3, the performance is significantly greater than that of a K6-2 - but as the motherboard supports both you could always opt for a cheap K6-2 now and upgrade to a better K6-3 processor when you upgrade the Ram (by which time the price of a K6-3 450 will be even lower).

As for the graphics card the best gaming options available for sensible money are 3Dfx's Voodoo 3 or any card based on a TNT2 chipset. 16Mb versions of either will cost about £80 and a 32Mb TNT2 card about £110.

So a motherboard (£55), 16Mb AGP graphics card (£80) and K6-2 475 (£65) could all be had for the £200 you specify as your available budget - although you could opt for a K6-2 400 and 32Mb TNT2 board now for the same money with a view to upgrade the processor later. One final point in reply: if a piece of software states a minimum requirement of Pentium 90 or 200, an equivalent clock speed AMD alternative will also be up to the task. An Athlon processor will certainly run games with Pentium requirements as it even outperforms equivalent clock speed Pentium IIIs.

One important first step will make the change easier if you're going to switch your graphics adapter at the same time: be sure to change your graphics adapter driver to Standard VGA before you shut down the old motherboard for the last time. This will save you any grief from the computer trying to use the wrong driver for the new adapter when you start up.

Before you shut down the old motherboard for the last time, go into your Registry and delete HKEY_LOCAL_MACHINE\Enum and everything under it. Next, install the new motherboard and then power up your computer. Plug and Play will go out and look for all the hardware and will leave your system properly configured for the new motherboard.