PSU help please

right i just fitted my new PSU and i for got to reconnect the end back to the unit :|
first thing was it start but litrally half a second later it died and all lights and power died
now i dont get nothing when i hit the power button not a sausage
what have i done ? and how do i fix it
please help im really desperate i have some very important coursework on there and im using my friends laptop to send thing
thanks guys
PS i know im a complete moron

 

What do you mean you forgot to reconnect the end back to the unit?

 

like my PSU has cables coming from and there is say 3 4 pin molex connectors on then a connector that i think is meant to return to the box am i right ?
well first time i turned it on i didnt have them connected to the PSU so i presume ive broke something

 

Return to the box? What do you mean by this?

Your power supply should have a power cord coming out the back of it that you plug into the wall.

On the inside you should have two cables that connect directly to your motherboard. A long rectangular bar with lots of wires, and a square 4 pin or rectangular 6 pin bar.
Each optical drive and harddrive should have a cable running to it, either 4pin or sata power. Your video card may need power as well, if you have one and depending on the card (some get their power directly from the motherboard). And then each fan in your case needs power either through your motherboard or through the power supply.

Your cpu fan should be plugged into the motherboard directly. There should be a 3 pin labeled CPU_FAN somewhere near the processor.
You should also have SYS_FAN labels on the motherboard to plug in 3 pin fans directly to the motherboard. You should so if they can reach, otherwise use the Power Supply cables

Nothing should plug back into the power supply. You should have plenty of unused connections and possibly cables when you're finished.

 

i dont know how to explain it
i have long cables that connect into my PSU box right and there are like 2 connecting ends on each one
1 molex then 1 really small 4 pin like a CPU fan connector but 4 pins both have slots on the PSU
and when i take the small one out all im getting now is like a small turn over on the fans
no shortage of power i know cause i upgraded from 450watt to 650 watt
only thing that might be is my cable to the wall is 250 volts but the PSU says 230 volts but this was the case with my older PSU and that worked fine:S

 

its deffinately not my motherboard or anything it must be the PSU
i have tried my old PSU with it and it works fine however when i try my new one i keep getting the blink from my fans and thats it
any ideas ?
before i send it back because id rather keep it as my new video card should arrive tomorrow and i dont want to be waiting another week or so to get my card up and running

 

i have now narrowed the fault down to my HDD its a maxtor SATA 160GB
when i unplug this from my PSU circuit like so there is no power to it it all works fine except it obviously cant boot but when i plug it it i get a short burst of power and then it all dies
please anything i can do as i have some quite valuble pieces of work on there

 

Sounds like you have a modular power supply. What PSU do you have for reference?

 

its a trendsonic 650 watt bought off ebay
and could you explain to me what you mean by modular ?

 

i have just tried to run the system with my old IDE HDD and it worked fine i will use that for now
i dont have another SATA HDD so i cant test a deffierent one
also i have just tried the SATA HDD with my old PSU i usually used it with and it came up with a message saying "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER"