The week before Christmas 2001, I acquired the components to upgrade my existing main PC from an Intel Pentium III 1 gigahertz to an Intel Pentium IV 2 gigahertz, which I hoped would give me the required oomph to better handle the CAD and the heavier image processing I do. I obtained the processor, heatsink and fan,  512 Megabytes of Rambus memory (the standard stuff preferred by Intel) and a spanking new ABIT TH7II motherboard. Pentium IV motherboards also require additional power supply connections, so a compatible power supply was also procured. This was my first foray into Pentium 4 territory, and I approached the upgrade with some apprehension. Here is the photographic record of the assembly... as ever, for a larger image, click on the thumbnails.

The TH7II motherboard... notice the small size of the processor socket, and the support bracket around it for the heatsink. Note also the seven segment diagnostic display in the top right hand corner.

The processor itself... the most expensive component, and yet the smallest. This is a Northwood 478 pin Pentium 4 - the very latest version.	The Processor heatsink... somewhat larger than previous types. This is clipped to the support bracket on the motherboard, in hard contact with the processor surface.	This is two modules of 256 megabytes of Rambus 400 Megahertz memory, plus two continuity modules that come with the board. Memory must be added in pairs of modules, unlike the Pentium 3.	The new-style power supply is mechanically identical to the older type but with extra connectors for the additional power required by the processor and memory.

The first thing to hit me was the physical size of the processor, barely larger than a 50 pence piece. Unlike the Pentium 3 chips I was used to, the processor was physically much smaller, and mounted on top is an aluminium heat spreader, to transfer the heat into the heatsink. The white gunk visible in the picture is heat sink compound... the suppliers shipped the board and processor/heatsink assembled, but I took them apart just to find out what was hiding beneath. The compound is necessary for efficient heat transfer, as the hotter the processor runs, the shorter its' life. The next shock was the size of the heatsink... a large, heavy chunk of extruded aluminium with a large fan on top. In order to support it, the motherboard is fitted with a bracket around the processor socket which allows the heatsink to sit on top of the processor without rocking. The heatsink is firmly retained by 2 spring clips which hook over the top, into the support bracket.

The memory was unfamiliar, too. A little larger than a standard DIMM memory module, these components are also fitted with aluminium heat spreaders to dissipate heat and provide electrical screening. I've never seen memory with a 'Hot - do not touch' warning sticker on it before. Supplied with the motherboard are two continuity modules, which plug into the unused memory sockets not occupied by memory. These close off the circuit connecting the memory to the system and are essential for the system to function.

The final pieces of the jigsaw are the motherboard and power supply. I chose the ABIT TH7II motherboard because I've always liked ABIT boards, and this one had particularly good reviews. It came with the facility to connect up to 8 IDE devices (hard drives, CD ROM drives, DVD's etc) as well as having great diagnostic features, including a 2 digit LED display which can display fault information in the event of hardware failure. This is an unusual feature, and one well worth having. For the power supply, I obtained a 300 watt model with the requisite extra connectors needed by the motherboard.

The old Pentium motherboard and ancillary equipment before removal. I use a desktop style case, which requires additional fans to provide forced ventilation because of restricted airflow within.	All the cables, cards and ribbon cables have to be removed before extracting the motherboard. The memory is also removed at this stage due to the vulnerable position in which it is mounted.	The motherboard is mounted on a removable base plate. Here the old motherboard and processor can be clearly seen. Note the coating of dust on the heatsink fan.	The new motherboard is now mounted on the plate. This is a fiddly job involving much cursing and several cigarette breaks. When complete, the assembly is turned upside down and shaken to check for loose screws.

The base plate complete with motherboard has now been refiited into the case... while the motherboard was out, I swapped the power supplies over. All cables and cards are carefully reinserted into the appropriate connectors.	It is essential to check all connections are now tight and in the correct orientation. A mistake could either be merely irritating or disastrous, depending. Space is very cramped, and it's quite hard to see what's going on.	Due to the heat generated by the processor and memory, it's essential to keep the areas around them as clear as possible. All of the flat, grey ribbon cables have been either shortened to minimise length or are tucked away. All other cables are clipped to the case in a bundle.	The completed PC is now ready for the big switch-on. I was a little nervous at this point, I can tell you. The case lid was left off to enable checking of the diagnostic display, the temperature of the heatsink, operation of fans and so forth.

Largely to my surprise, the PC booted first time and recognised the correct amount of memory - the manual for the motherboard was fairly vague as to how the memory and continuity modules should be arranged in the slots provided, and I wondered if my arrangement was correct. On first boot, the machine had to establish what processor it had fitted... and to my surprise, the BIOS (Basic Input/Output System; the code that is responsible for controlling the board)  didn't recognise the processor correctly. I powered down, and accessed the ABIT website from another PC to see what information they had... to my relief the most recent version of the BIOS added support for the latest Northwood processors amongst other changes. I downloaded the bios programming utility and latest code onto a floppy, booted from a boot floppy and went through the upgrade procedure. Upgrading a BIOS is a hazardous procedure, as any failure during the process can render the board useless -  the cigarettes took another hammering. Thankfully, the update completed, and after clearing the CMOS memory (this is a small area of RAM responsible for maintaining the settings of the PC and is backed up by battery) the processor was detected correctly. I went into the BIOS setup screens and checked the settings for the processor, memory and drives. Content with these, I checked the temperature and hardware monitor information and these appeared fine, too. Rebooting the machine, I expected windows XP (my operating system of choice) to crash, but after a little to-ing and fro-ing, windows settled down happily. I always erase the previous operating system and reinstall again after such a major change, but with the system appearing settled, I ran some applications to see how fast the machine now was... and it flew. The cad sprang to life, no flickering on the display, no pauses. I tried some games, these too, performed excellently. I was extremely impressed with the way the system performed... windows seemed a lot more responsive, and tasks such as thumbnail generation (formation of small icon versions of larger images) were seemless.

Screenshot of BIOS setup screen showing processor information. The items in light blue are items set up automatically by the motherboard.	Another screenshot showing the hardware monitoring in action. See how the BIOS monitors power supply voltages, fan speeds and temperature of various aspects of the PC. An alarm will sound if any of the fans stop or the processor temperature increase above 65 degrees.	A screenshot from within windows: this is for the technical people amongst you. I notice that the motherboard now allocates interrupts above 15... this never occurred under the Pentium 3 and breaks with a long-held constraint on PC architecture.

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