Last updated: 12 June 2004
Here's an already quiet machine I built for my Dad's home office a couple of months ago. I recently added this neat mod using an old Weetabix cereal packet (hence the page title - you will only understand if you live in UK!), as a shroud to direct the airflow through the fins of the CPU heatsink.
OK, here's the machine spec, which was built with two main criteria in mind, price and quietness. Performance was not in issue, as long as it is capable of running Windows XP and basic office applications, which is why I went for a low power Via C3 CPU:
MSI MS-6368 mini-ITX motherboard with built in video, sound, LAN
Via C3 800MHz CPU, passively cooled with an old Athlon heatsink
Seagate Barracuda IV 40GB hard drive
250W generic PSU with fairly quiet fan (no other fans in the entire system)
Generic ATX case
CD Rom, CD writer, 256MB RAM etc
Total cost (using mainly second hand parts from Ebay) was just under £200 - the budget imposed by my Dad!
The photo below shows the general layout, the modem is the only PCI peripheral as everything else is on board. I could have easily fitted this into a Micro-ATX case but size/beauty weren't an issue, especially as I managed to pick this case up for a tenner! Note the (not particularly neat!) cablegami which keeps the ribbon cable out of the airflow.
Looking into the cardboard shroud. This took me about 15 minutes in total, so it is slightly wonky but works well. Due to the layout of the board, the fins of the heatsink run up and down, perfect for this arrangement. I used duct tape to cover up some of the PSU holes and hold the shroud in place. But there are still plenty of holes sucking the air through the shroud, across the heatsink fins.
This shows the positioning of the Barracuda IV hard drive. I cut the fan guard out, and screwed another 3.5" drive bay directly in front of it and put the hard drive in that so the air flows right across it. I've duct taped all other case holes, so this is the only way air gets into the case.
This shot of the back of the case shows how I've covered up all the fan holes and other holes except the PSU fan, which I cut out the stamped grille and replaced it with a wire one.
Here you can see I've opened up the slot in the bottom of the bezel, to allow air into the case more easily. The "On" label was put there by my Dad, so he remembers which switch is which!
This cardboard shroud mod wasn't really necessary, as maximum CPU temperatures under load was never going above about 55°C, which the C3 can more than cope with. But as an experiment I wanted to see what difference it made so here are the results. All temps were taken as averages over a 24 hour period, before and after the mod. Room temp did not vary much.
| Before | After | |
| CPU | 36.8°C | 29.1°C |
| Hard Drive | 28.3°C | 27.2°C |
| Case | 26.4°C | 23.6°C |
As you can see, it has made quite a difference to the CPU, nearly 8°C. Not bad for a half hour job that didn't cost anything. The hard drive is as expected, no significant difference. The case temp may be because of a slight difference in ambient, or the thermal diode is somewhere near the duct. Of course this mod wasn't really necessary in the first place, but it goes to show that there is now more cooling headroom with this setup, which means there should be room to upgrade to a faster CPU should it be necessary, perhaps a 1GHz C3 Nehemiah or a Celeron Tualatin, with no additional active cooling required. Also I can now relax if we have another hot summer, knowing that even if it gets to 38°C again with no air conditioning, the PC will still work fine!
Performance is no great shakes but more than adequate for running office applications, email and web surfing, which is all it will ever be used for. A faster CPU would make next to no difference for these applications. It is almost completely inaudible in a quiet office environment, due to its single fan and Barracuda IV hard drive. Overall I'm very pleased.
Pangit