Hi
Routers based on the Broadcom chip (equally applies to the other chipsets), regardless of how hot the case feels (which is very subjective) get very hot. The chip itself is rarely heatsinked and I've measured temperatures of 70-80 degrees on the chip itself (using infra-red thermometer).
Silicon can run at quite high temperatures just fine so 70 to 80 degrees is probably okay (the plastic package is likely to fail before the silicone due to excessive heat) but the life of silicon chips is shortened quite a bit for rises in temperature.
The main problem is the circuit board and surrounding components are used as a crude heatsink so they all warm up. Capacitors which are not far removed from being just cans of spiralled wetted blotting paper age very quickly in continuous heat, and the soldered legs conduct heat from the copper tracks into them like dry central heating.
Most problems (rebooting, inability to hold a connection, freezing, not turning on) with routers after 12 months or more of continuous operation are most likely due to capacitors having dried out and aged so they longer do their job correctly.
Very occasionally a router with a Broadcom chip will ship with a heatsink (I've seen them D-Link 2640Bs) however they are only tiny and without very good venting or active cooling the heat stays in the box anyway. I've fitted a slab of a heatsink from an old Nvidia graphics card to my Broadcom chip and even with this huge chunk of metal and the top lid completely removed it gets hot and reaches 40 to 50 degrees. Turning the router on it's end may help but mostly it just stops a hot spot on the plastic case, inside the Broadcom chip will still be running very hot.
Really for 24/7 operation active cooling is required or a very good heatsink and venting design to remove the heat from the box, but adding this would increase the cost considerably and an active design would not be silent and so wouldn't be liked by everyone. Tiny cheap stick-on heatsinks little bigger than the chip itself don't really help and can become detached during shipping (unless a more complicated fixing is used raising cost again) causing increased returns.
These routers are very cost sensitive, essentially you are buying a small Linux computer with 4 network cards, a Wi-Fi dongle, some RAM and flash memory, powersupply and an ADSL modem, plus software for around £40.00 to £100. The manufacturer isn't going to want to erode profit or be uncompetitive by implementing a decent cooling solution if it can get away without doing.
Having an inbuilt obsolescence (they don't last long!) with a product that hasn't changed or advanced really for many years (the same Broadcom chips are used in the very latest models that were used in models 4 or 5 years ago) is no bad thing for the manufacturer as it creates ongoing sales where there would be few, as once bought few will replace them unless they break. I personally think SpeedTouch deliberately case their routers with very poor ventilation in order to cause more early failures. As they supply ISPs who supply them to their customers, I bet their sales model is to sell each unit extremely cheaply, to the ISP, when they fail the ISP then needs to buy a replacement, providing ongoing income for SpeedTouch or their distributors. This is the only explanation I can think of for ISPs (such as Be/O2 and others) for supplying these boxes that most would rate as very unreliable.
Regards
Phil
