Ohh right I see.
Well yes of course a Corsair Force GT is way faster haha, it's also way more expensive. Which is why I recommended the Vortex 4, which yeah I personally wouldn't buy, but you can't afford to be choosy when you're on such a strict budget. And to answer you, a further upgraded GPU from the 650Ti Boost would mean lowering everything else, which with the current components already being rather stretched, he would simply have a decent GPU, but everything else would be completely poop. But yeah, 1600MHz.
The force gt is around 65€ so it should be around 50 pounds. And my idea was to then spend the other 50 on a gpu, so no downgrading.
But op's limit was 400 pounds anyways, we missed the monitor.