i purchased LED lights and some flickered and died out what's the problem?

No transformers needed for GU10. Are you sure there is not a break in the supply to the lamps affected either live or neutral. If you do not understand the meaning of a break in live or neutral then you realy do need to get someone who does to check it out for you. But an easy way to check if it is a dimmer problem is to put back the standard GU10 lamp and see if that works ok-if it does then you do not have a break in live or neutral. As stated below a lot of LED's are not dimmable but if they are take note standard dimmers usually have a range between 40w-250w so you would need 8x5wat lamps to get into this range, you can get dimmers rated from 10watts so these would opperate with only 2x lamps plus at 5watts. Hope this helps but without a reasonable understanding it may not and you may need to get help. Kevin.

GU10 lamps both standard halogen and LD are mains voltage so unlike MR16 low voltage spotlights there is no transformer fitted or needed. Two possible things spring to mind, one a loose connection somewhere as all lights being affected at the ame time suggest a wiring issue and not lamp failure? The second posssibility is that you have a dimmer switch fitted to the lights? The vast majority of LED lamps are non-dimmable and so its worth checking the switch especially if its a dimmer. If not then it sounds like a small £20 job for an electrician to call to take a look and do some tests to diagnose the problem.