Hardware Game: Round Two

Sunday, 13 March 2005

Welcome to the second article of a series that looks at exactly what is involved in building a custom PC. In the first article, I explained how the unexpected demise of a graphics card precipitated my decision to build a new PC. I then covered how the processor, motherboard and graphics card might be chosen in a new PC. In this article, we have a look at storage, memory, the motherboard again and finally, the PSU.

Storage

Your PC, of course, will need storage. At the very least, you'll have a pair of Parallel ATA/IDE connections on the motherboard, which can be used for hard drives, CD-ROMs and more. Each IDE connection can hook up two peripherals, one set as master and the other as slave. The jumpers on the back of a drive will set which role it will take.

Note that it is not a good idea to put the main hard drive with the CD-ROM as they can conflict during common operations. For the same reason, a backup hard drive should not be attached to the same IDE connection as the main hard drive. My own setup has the main hard drive hogging the primary IDE connection, and the secondary IDE connection is shared between the DVD-ROM and backup drive.

However, putting aside portable storage, using IDE is not the only way to attach a hard drive to your system. The faster SCSI interface has been available for years, but SCSI hardware is expensive and typically used on workstations and higher-end machines. The new champion taking over from Parallel ATA is the Serial ATA (SATA) interface, appearing on many modern motherboards. I could also mention RAID, as many motherboards now come with a RAID controller, but this is usually a requirement for server systems.

What I needed was IDE interfaces for my existing peripherals - two hard drives and a DVD-ROM drive - but I was also interested in upgrading to SATA in the future. The motherboard I chose in the end also came with a RAID interface, but I doubt I shall make use of that.

As for hard drives themselves, well, I hear Maxtor are reliable but are going to fire more staff soon. There are two Maxtor drives in use in our household.

Memory

My previous PC had 512MB of memory and I wanted its successor to have 1GB of memory with room to upgrade. Some of the more recent 3D extravaganzas need a lot of memory otherwise they have to use the hard drive to make up the difference, which makes the gameplay stutter. Elocution lessons are not helpful here. Work with video or graphics can also make high demands on memory.

Research into memory, though, took significantly longer than I had expected. Buying memory is not a straightforward affair. There are two reasons why. First, a chosen motherboard will only support certain types of memory. Secondly, even if two different types of memory are both supported by the same motherboard it is unlikely that they could be used together.

The humble DRAM module has gone through a number of design cycles. Legacy memory technologies include the Fast Page Mode DRAM (positively Jurassic), EDO DRAM and SDRAM. Intel tried pushing an alternative (Rambus DRAM) in an effort to increase their influence over the hardware market but that, luckily, has gone the way of the Dodo. The current standard is DDR SDRAM but a newer standard, called DDR-2, is now entering the market. A modern memory purchase, provided your motherboard is willing, should be of DDR type, DDR-2 if possible. DDR-3 has just entered the prototype stage and is unlikely to be seen on the market until 2006 at the earliest.

Memory can also be categorised as unbuffered or registered. Registered memory is the more expensive of two and is only used when your machine is going to have a much larger memory pool than 1GB. It is typically used on servers to reduce the access time for a large bank of memory. For a desktop PC, there is little need to buy registered memory.

There is yet another cool way to increase the price of memory. Add another amazing acronym to it, ECC, "Error Collection and Checking". If the memory suffers an error and data is corrupted, the consequences can be serious causing an instant crash in the system. This kind of error is not due to faulty hardware, but due to naturally occurring phenomena and non-ECC memory has no defence; suddenly, the PC goes down. Although such events are likely to be rare, if stability is of paramount importance, ECC memory can not only catch such errors but repair them too. Personally, I do not think that ECC memory is necessary for a desktop machine, but the memory vendors would probably disagree.

Okay, so the last few categorisations have been straightforward, but this next one is more interesting: single channel or dual channel memory. To increase how much data can be moved in and out of the memory, some modern motherboards support two "memory pipelines" instead of one.

However, the memory has to be installed in pairs and you can buy more expensive "matched" pairs of memory. A matched pair means the two modules have been tested together in a dual-channel system. There is some contention over whether it is necessary to buy matched pairs of memory – some PC owners have got away with buying two modules of the same type instead of a marked-up matched pair. If you do buy unmatched pairs, make sure they are at least from the same manufacturer and of the same memory type.

This brings me to memory speed, which is a measure of how much data the memory can send or receive through the motherboard. Of course, the faster the memory, the more expensive it is. Memory speed can be measured as memory frequency (200 MHz), DDR rating (twice the frequency, such as DDR400) or bandwidth (eight times the DDR rating, PC3200).

Anything else to worry about? Yes, there is also latency to consider. Latency is a measure of how long it takes the memory to process data and so the lower the latency, the faster the memory operates. It is often quoted briefly as a CL or CAS number (e.g. CL2.5), but you will also see latency quoted as a quartet such as 2-2-2-5.

Latency and memory speed are easily confused, so let's clear the air here. Latency is an internal parameter of the memory and there is no association between the motherboard and memory latency. Memory speed, on the other hand, is how fast the memory interacts with the motherboard and so a motherboard capable of supporting the speed rating must be used.

A motherboard will only support a limited set of memory module types even with BIOS tweaking. To buy the latest and greatest memory after waiting for years is just like buying a new processor; get ready to open the window and give the motherboard your best shot. Check the motherboard specifications carefully for the types of memory supported.

For graphics or gaming applications, faster memory assumes more importance. DDR-2 motherboards were not available at the time so I purchased 1GB of DDR400 with low latency timings of 2-2-2-5 as a matched pair of 512MB modules for a dual-channel motherboard. I also looked for reliability as cheap RAM can double up as dodgy RAM (bad RAM will assert itself by crashing the system inexplicably from time to time) so chose Corsair, expensive but with a solid reputation.

If you want more information, Corsair have some great documentation on their site. In particular, explore The RAM Guy's Tech Notes and, if you intend to buy Corsair, their compatibility search is extremely useful. Elsewhere, there is also an interesting but technical comparison of latency and memory speed.

Case and Motherboard

Most of the important decisions have now been made and it is clearer what kind of motherboard will be needed. It is sometimes not possible to choose a motherboard that fits all of the requirements and some give and take may be required. The chipset, the hardware that runs the motherboard (which differs from the BIOS, the software that runs the motherboard), may also be a factor in the decision. I really, really do not have enough expertise with chipsets to make any suggestions and I just tried to make sure the chipset was fairly recent and there were no hideous reviews out there on the web. In the end, I chose the ASUS A8V Deluxe, a relatively new Socket 939 motherboard by respected manufacturer ASUS, built on a VIA chipset.

We have almost finished our purchasing decisions. Now if you are not going to reuse an existing PC case, you will need to buy a new PC case. The only measurement of a case which can completely screw you up is the motherboard form factor (loosely speaking, the motherboard dimensions) it is capable of supporting. Many motherboards come as the ATX form factor, although it pays to be wary particularly as Intel have been trying to push a new BTX form factor standard.

You need to decide whether a tower PC case or desktop model would best fit in your workspace but after that, what else needs to be considered? Two things; ergonomics and airflow.

What I mean by ergonomics is how easy it is to install bits and pieces inside the case and manage the unavoidable mass of wires. It is best to go searching for reviews to find out what are popular cases in this respect. For example, the Thermaltake V7000A case has a hard drive rack that needs no tools to install and similarly card extension slots that do not use screws (although in this model they do not cope with tall cards and you have to revert to screwing them down, later models do not suffer from this problem). It also has a clear window on the side so that the inside of the PC can be seen, allowing limited diagnosis of problems without opening up the case. Lots of space although it does not have a removable motherboard tray. I should point out that the blue glow has no major benefit to the ergonomics.

Airflow is important when you have a PC likely to get quite hot. A top processor and a monstrous graphics card will generate a lot of heat and that needs to go somewhere. What I liked about the Thermaltake case is that it had multiple fans to maintain good airflow throughout the interior, helping to tame the major hotspots. Further, there was plenty of space inside, meaning that air could really flow. A nice extra is that all of the fans had a filter so I would be able to see the motherboard and not a dust desert when peering inside the case - a common sight if you have had a PC for any length of time.

To conclude this discussion on cases, I have also heard good things about Lian-Li cases which look a great deal more serious and less like teenage geek toys.

PSU

One last stop before proceeding to order the components and build the PC. Every PC needs to take power from the mains and share it out amongst the various components. This is the role of the Power Supply Unit (PSU).

When choosing a PSU, it is important to make sure that it can supply enough power and that it matches the form factor of the motherboard. The PSU will be rated in Watts, the energy it can deliver per second; my old PSU was 350W. My new machine was definitely going to require more power, but how much?

I browsed a number of sites on the web that gave instructions on how to calculate the power usage of a PC, but they all disagreed. Even worse, some of the numbers I calculated came out impossibly large. In the end, I decided to upgrade to a bigger PSU just to be on the safe side. I chose a Thermaltake Purepower Butterfly 480W ATX PSU.

There are other issues to consider. A PSU can get very hot and needs to be effective in controlling its own temperature, which means PSUs always have a fan inside. The fan may be noisy and PSU reviews usually spend some time on how annoying the PSU fan is. Also, the power output must be fairly consistent, otherwise components are likely to experience difficulties leading to - in the worst case - system crashes.

Finally, make sure it has power connections for the different components that need to be fed. Floppy drives and SATA drives, for example, use different power connectors than the standard D-shaped power plug. This was a fact I was not clued up on before ordering a PSU, although I was fortunate to get everything I wanted. Perhaps there is a Santa after all.

Time Out

That concludes not just the second part of Hardware Game, but the planning stage. In the third part, we will look at the construction of the PC, things that went wrong and some final thoughts on the game.

End