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More Power!

AMD’s like big power supplies. Really big.

When the Athlon first appeared, there was some surprise at AMD’s recommendation that PC builders used a minimum power supply rating of 300W. Most PCs at the time ran on 200W or 250W so this seemed like quite a hike. A few people tried to get by with 250W but it soon became apparent AMD weren’t kidding and a stable system needed the full 300W.

A Curious Problem

One of my test PCs has been happily running 24 hours a day, seven days a week for a few months now. It has never crashed or showed any sign of disk corruption. It was a happy PC.

Then I added a DVD burner and the problems began. Every disk I burned failed the verify stage with typically between 2 and 5 bytes being bad across the 4.7Gb surface. I tried some experiments writing 3 or 4 big files and thousands of small files. In each case the results were the same – a small number of duff bytes. The first assumption was that there was a driver problem. Many evenings were spent updating and tweaking the various drivers that might be affecting things. No change, in fact some changes made it far worse. Still, the fact drivers were affecting things made me feel I was getting close.

Diagnosing

Eventually suspicion fell on the drive itself and it was duly swapped out by the supplier. The replacement alas showed the same symptoms (oops). I now started to wonder if it was just immature Windows XP motherboard drivers so I decided to purchase a PCI based card to connect the DVD burner to. That way I would be isolating the particular chipset the motherboard had built in and perhaps that would solve the problem. Nope.

At this point someone suggested checking the RAM. Surely not? I would have expected crashes galore if the RAM was faulty. I went to www.memtest86.com and downloaded their rather excellent memory test program. This freeware tool can be downloaded in various forms including a bootable CD image to guarantee it has full access to the hardware unhampered by any operating system issues. It was left running overnight. In the morning I was amazed to see 110,000 memory errors.

More testing showed an interesting quirk. Any tests that used the CPUs built in cache failed but those that involved disabling the cache passed. So now the finger of suspicion fell to the CPU. It looked like the CPU had a damaged level 1 or level 2 cache. A quick search on Google revealed this wasn’t unknown on Athlons so the CPU was sent back for testing and hopefully replacement.

A few days later the bad news came, the CPU tested fine. I double-checked they fully understood the issue and that they should be checking it with caches enabled then disabled. Yes, they’d done that. What now?

During diagnosis a common suggestion from different people I asked was to fit a beefier power supply. As the PC only had a single hard drive, the graphics card and a network card, this seemed unlikely. On a heavily hardware laden machine I could imagine 300W starting to look a bit puny but on such a lightweight machine? Well, it was possible.

I had a quick look around at noticed Antec had a new range of PSU’s available. I’ve had a soft spot for Antec after looking at one of their cases recently so had great hopes for their new PSU series.

The Antec TruePower range comes with a variety of outputs from 330w to 550w. In this case Antec sent me a 380w model that normally retails at around £64. The TruePower range has a number of interesting features (no really, PSUs can be interesting) so lets go over those now.

The unit has two big cooling fans but unusually these are controlled by a temperature sensor inside the PSUs housing. If it starts to get warm, they kick in. If it gets warmer, they go faster. The fans adjust themselves constantly to the requirements of the unit resulting in much less noise than some of their peers as they will only spin as fast as they need to. For people who have additional case fans, you may be interested in the dedicated power connectors for them linked to the temperature sensor allowing your case fans to change speed too to suit the ambient temperature.

The other prime feature and quite possibly a unique one as I’ve not come across it before is the way in which the different voltages are handled. Normally a PSU supplies 3.5v, 5v or 12v to the different cables. In particular, the same circuit in the unit handles the 3.5v and 5v lines. This can result in stability problems. Whilst a PSU has an overall rating, say 300w, if the machine has a lot of drives, they may take more than their fair share of the capacity with a resulting drop in available power to one of the other voltages – perhaps the one feeding the motherboard. This can make some systems a bit flaky. The TruePower range has separate circuits for each voltage and as such provides a far more stable supply. With an Athlon based system, this can be doubly important. A final tweak to the design is that the tolerances are accurate to +/- 3% instead of the more usual 5%.

Fitting is straightforward. Simply unplug the old PSU from all the drives, motherboard and fans and unscrew it from the case. Usually this involves 4 screws at the back of the PSU. Once done, put the new one in, plug all the cables back in and you’re done. Rather oddly, given that the new PSU is Antec and the case it was going in to was an Antec, I did have to make a minor adjustment to the case to make it fit by bending back a support panel to allow room for the internal fans grill.

I have to say, I never thought I’d get enthusiastic about a PSU but the Antec unit is very well engineered. It oozes quality and even the gold grilles over the fans seem to add a little something. If you can afford the premium price, this unit won’t disappoint you, it‘s a superb PSU both technically and in build quality.

With the beefier PSU in place, it was time to check the system out. It was with great relief that the memory tests passed with flying colours indicating that the new TruePower unit was indeed supplying the extra juice the system needed.

Conclusion

Athlons need a lot of power. With the faster versions and their generally higher current draw, this becomes even more important. A 300w PSU may well cope fine but if you find your system crashing mysteriously or generally behaving oddly and you’ve exhausted all other avenues, you may want to consider fitting a better PSU. Whilst these can be picked up quite cheaply with basic ones starting at around £25, you may want to consider something a little more upmarket for peace of mind. With its better handling of the different voltages and variable speed (and thus quieter) fans, the Antec TruePower range is well worth checking out.