During a discussion on a web forum, I put forward the claim that for heavy usage scenarios buying a power supply that delivers twice the wattage required can add up to energy savings. This was brought into question, so I devised a neat little spreadsheet with three simulated scenarios – the result of which I have reproduced below.

Using several assumptions, I built three models: a gamer who plays two hours a day, a pro-gamer who plays eight hours a day, and a folder or miner who has the system fully loaded 24 hours a day. Each of these users is building a new rig, the specifications of which are given below. In all three cases, it’s a completely new rig: no existing parts are being used. The models compare the energy used by two otherwise identical power supplies, one of which is running at at near-full-load and the other one at half-load – and compare the energy savings that come from the fact that PSUs are naturally more efficient at 50% load. Actual figures for this increase in efficiency, taken from the official 80 PLUS certification requirements, can be found in the Assumptions section.


  • Radeon R9 290(X) TDP: 300W
  • Intel Core i7 4770K TDP: 84W
  • Motherboard, Fans and So Forth: 40W
  • Non-Green Hard Drive: 8W active, 3W idle
  • Total maximum system power draw: 432W.

When gaming, the GPU is 100% loaded and the processor 60% loaded (two cores versus all four cores, plus overhead), while the hard drive is mostly idle for a total power draw of 393.4W rounded down to 393W for simplicity’s sake.
When participating in distributed computing projects like Folding@Home or Litecoin mining, both CPU and GPU are 100% loaded, while the hard drive is mostly idle for a total power draw of 428W.
Electricity currently costs on average 15.32p per kilowatt hour (KWh), based on figures from the Energy Saving Trust. From the same page, generating each KWh of electricity causes 0.517kg of carbon dioxide to be emitted into the atmosphere.
The cost of electricity is rising at 7 per cent annually, based on an average of the most recent price rises listed on USwitch.
The PSUs in question have a five-year warranty, and thus five-year worst-case lifespan. All calculations, therefore, are based over a five-year period.
The two PSUs under comparison are both 80 PLUS Titanium rated, one at 450W and one at 900W. As a result, at the system’s peak load the 450W offers 91 per cent efficiency, and the 900W offers 96 per cent efficiency – both minimum efficiency figures at 100% and 50% load respectively as required by the 80 PLUS certification. Buying the 900W PSU costs £50 more than the 450W PSU.

With that in mind, let’s run the numbers.

The Gamer
The gamer works in an office all day, during which time his or her PC at home is powered off. On average, the gamer manages to get in around two hours of gaming every day – some days there’s no gaming at all, but on a weekend it might be an eight-hour marathon. At all other times, the computer is switched off or in an extremely low power mode.

Result of Simulation:
Over a five-year period, paying the extra £50 for the 900W PSU will have cost the user £36. In other words, this use-case makes no financial sense. Additionally, however, the move will have reduced the environmental impact of the PC by preventing the emission of 8.49kg of carbon dioxide into the atmosphere.

The Pro-Gamer
The pro-gamer works at gaming all day. Eight hours a day, seven days a week he or she is hammering the system, honing skills and pwning the opposition. Outside the ‘office hours,’ the PC is switched off or in an extremely low power mode.

Result of Simulation:
Over a five-year period, paying the extra £50 for the 900W PSU will have saved the user £8. Not much, but it is a saving. Additionally, the move will have reduced the environmental impact of the PC by preventing the emission of 33.96kg of carbon dioxide into the atmosphere.

The Folder
This user has their system forming part of a distributed computing cluster. Perhaps they’re running Folding@Home or BOINC for scientific research, or renting their system out as a renderfarm, cracking passwords and generating rainbow tables, or perhaps they’re trying to mint the latest cryptocurrency. Whatever the reason, the system is at full load – CPU and GPU – all day, every day. Hey, on the plus side: at least their room is nice and warm.

Result of Simulation:
Over a five-year period, paying the extra £50 for the 900W PSU will have saved the user £139. Hey, that’s enough to buy a replacement PSU! Additionally, the move will have reduced the environmental impact of the PC by preventing the emission of 110.94kg of carbon dioxide into the atmosphere.

If you only load your PC for a couple of hours a day, don’t bother speccing it with a PSU capable of delivering double your wattage requirement. You’ll never recoup your investment, and the environmental impact is minimal. If you’re a pro-gamer, it could be worth doing – especially as you’ll be able to claim the cash spent on the PSU as a business expense against tax, something I didn’t take into account in my calculations. If you’re a folder, though, absolutely go for maximum efficiency – it has a real-world environmental benefit and gives you the cash you’d need to replace said PSU once it’s out of warranty. Win-win!

The WePad slateAll this talk in the media about the iPad – and there’s plenty of it, with an estimated 80% of the articles in my RSS feeds over the last few days being iPad related in one way or another – has whet my appetite for a slate-style device, but one that offers a little more flexibility than Apple’s locked-down PoS.

The first thing to catch my eye was the WePad from German manufacturer Neofonie.  The specifications call out to me – 11.6″ 1366×768 display, SDHC card support, USB ports, Android operating system, and a 1.66GHz Atom processor all pretty much crap on the iPad from a very great height, with the sole exception being the mere 6 hour battery life to the iPad’s 10 – and it looks shiny enough, but sadly it’s not yet available to buy.

Okay, so Android – if not rooted – is still a locked-down platform, but compared to the iPhone OS – as found on the iPod Touch, the iPhone (obviously) and the iPad – it’s as free as a kilt and no knickers.  Neofonie has even promised that, despite the fact they’re aiming the WePad as a platform for its WeMagazine digital publishing platform, full access to the Android Market will be granted – meaning third-party applications can be installed without restriction.

I’m still undecided as to the relative merits of the slate form factor, but the WePad has certainly got my attention – and not just because it sounds like a euphemism for Tena Lady.

With the missus getting increasingly addicted to Guild Wars, it’s been getting harder and harder to get on my PC of an evening.  Accordingly, I have treated myself to a new toy – an Acer laptop.

The specs are reasonable, although I could have lived without Vista.  It’s taken me almost a full week to beat the thing into submission – it’s amazing how irritating Vista is when you’ve used a grown-up operating system like Ubuntu for a while.  Actually, that’s the next step – dual-boot the thing, with Vista for games (and Blu-ray playback) and Ubuntu for actually getting things done.

One thing I’ve noticed about the specifications, actually: it’s fitted with an ATI Radeon Mobility 3470 chipset, but CPU/Z shows it as a 3450.  I’m assuming this is an artifact related to the fact that I removed the crippled drivers provided by Acer and replaced them with hacked desktop drivers based around the latest Catalyst version.  The new drivers work fine – and with the performance of a 3470 – but display as a 3450.  Strange.

All complaints – and between Vista and some of the stupid things Acer has done, there’ve been a few – aside, it’s a reasonable new laptop, and it only set me back £470.

Oh, and in honour of its status in the house it’s been christened TOYBOX – after the debris recovery vessel from Planetes.

In a brave attempt to rid myself of some of the cruft I’ve gathered over the years, I’ve recently had a somewhat brutal clearout.  As well as all the rubbish that I’ve collected, I’m planning to get rid of the vast majority of my old gaming equipment – including my beloved Commodore C64 collection.

Accordingly, I’ve put a page on this ‘ere site called – surprisingly – For Sale, which contains – again, surprisingly – a list of all the items I’ve catalogued.  The page will be updated just as frequently as I can bring myself to, with the easier-to-catalogue stuff getting added first – which means that the C64 with its two large boxes filled with games will likely be last.

If you’re interested in any of the items you see, make me an offer either via e-mail or through the comment link on the page.

I’ve been on a massive clearout session of my old computing stuff with a view to finally decluttering my life after twenty-some years of being an unrepentant hoarder, and I spotted an old brochure lying in the bottom of a box.

Just think – for under £3,000 you can get an ‘ultimate games machine’ with a Pentium 200MHz CPU, 32MB of RAM, and a whole 3GB of hard-drive space!

Let’s compare to my mobile phone shall we?  ARM 266MHz, 16GB of usable space, 64MB of RAM…

I wouldn’t mind, but this was only 1996…

I finally got around to recording just how long my Eee PC 701 lasts for under normal usage.

EeePC 701 Power History (23k image)
That’s with almost minimum brightness, playing music and browsing the ‘net. It’s not the greatest battery life ever, but pretty impressive for the size.

To be fair, I shut the system down when the battery light started to flash. The version of Unbuntu I have installed doesn’t read the battery life properly – despite reporting 28%, there was probably only about 10% left. I know that //last// time I left it running, expecting auto-shutdown, it ran out of juice and crashed hard.