Hanging up/long delay at mobo screen

Hello all,

I was having some heat issues with my cpu so I got a new heatsink and fan and installed it today, and after install I start up the computer and up pops the graphic screen that says the motherboard brand and model and press del to enter setup or tab to display post bios, and it just sits there so I start sweating thinking I screwed up somthing, but after 2-3 min it goes on as normal windows starts and the computer works no problems.

I played a graphic and cpu intesive game for several hours and had no trouble so I restarted the system and the same thing, hangs up at that mobo screen then starts fine after a few min, and when its on that screen if I hit del or tab nothing happens, no setup or post.

System;
Asus p5n-e sli mobo
intel core 2 duo E6750 cpu
3 gig ram
Evga GTS450 GPU
windows vista
and the heatsink/fan I just installed; Cooler Master RR-910-HTX3-GP Hyper TX3

 

also wanted to add, if I restart and try to bring up setup, it never comes up even if I start spamming del before shutdown is even done, just tried it so I could post some settings to help you all help me, hit restart and when the screen said windows is shutting down I started hitting del every few seconds untill the windows loading screen came up (with the delay I am getting, about 3-4 min)