Toto Wolff has admitted Mercedes is pushing the boundaries of its performance to defeat Ferrari in its tight title fight, ultimately leading to its recent spate of gearbox failures.

Lewis Hamilton was given a five-place grid penalty for the Austrian Grand Prix after the gearbox was swapped on his W08 ahead of qualifying, before Valtteri Bottas suffered an identical fate at this weekend's British Grand Prix.

Having prided itself on establishing a superior reliability record since the start of its title-winning run in 2014, Mercedes admits the trend of failures is a worry for it at this stage of the season.

Even so, Wolff believes it is simply a symptom of extracting performance from its W08 in its fight with Ferrari.

"We are trying to push every area and extract performance wherever you can and sometimes you go one step too far. We damaged both gearboxes in Baku and we hope to survive until after Budapest with Valtteri's but we didn't want to take the risk.

"Now both gearboxes have been changed back to the safe spec, where we shouldn't be having these problems anymore. But it's just the new reality and you just need to not leave any stone unturned in order to find performance."

Indeed, Wolff says the 'maturity' of the gearbox technology means it can only go so far with performance extraction.

"Unfortunately the gearbox is quite a mature area and there is not much performance you can extract, so that is not a big performance differentiator. Nevertheless, we have tried it in order to maximise it, but it's not that you would really see it on the stopwatch."

Hamilton finished fourth in the Austrian Grand Prix having started eighth, while Bottas will get away from ninth at Silverstone having won last time out in Spielberg.