Problem with GTX 460 after installing new cooler

[raiken]

I have a GTX 460 1GB OC produced by Leadtek. The stock cooler was very loud, so i decided to change it with a new one from Deepcool (V400). After install it, I started to run FURMARK. After about 8 minutes, when the GPU's temp reached 73 degrees, my display went blank and my computer stopped working. (The card equipped with stock cooler worked fine and was stable at 75 degrees). So, I reset the comp and i received 1 long beep followed by 2 short ones (meaning i have problem with video card - ami bios). At that moment i turned off the computer, and after 2-3 minutes I turned it on again - and worked.
I want to mention that on idle i have 27-28 degrees on GPU (instead of 33-34 with stock cooler) and in 3D Mark Vintage i reached 49 degrees instead of 58-60 (with stock cooler). In conclusion, this new cooler is better, but why the video card is turning off at 73 degrees and with old cooler is working fine at 75 degrees?

Dunno if this is important, BUT! the V400 from deepcool came with a 12 cm fan. That fan doesn't have same connectors like the old one, so i connected it to MB. (The 12 cm fan has 3 pin jack and is bigger than the original GPU fan which is having 4 pin jack).

It is possible to burn my video card if I will start new tests in furmark? Or it is protected and that's why it is shutting down at 73 degrees?
ALSO! I NEVER overclocked it.

Sorry about my english. I hope to understand what I tried to explain.

And please give me some advices.

Thank you,
Greets Razvan

 

[vigilante212]

The 4 pin fan will increase speed as the chip heats up the 3 pin will not. Also double check your seating of your fan/heatsink maybe you missed something.

 

[raiken]

I missed nothing. I've checked it many times.
Right now the 12 cm fan is connected to motherboard. And as i mentioned, the idle temps are around 28 degrees.
Is it possible to take out the fan jack from video card and to insert the 3 pin connector in there? (video card fan jack is smaller than fan jack and also it has 4 pins. If i take it out from there, I will be able to insert my bigger 3 pin jack)

Here is a link with a picture of my video card. In the bottom right corner u can see the 4 pin jack which is smaller than 3 pin fan jack
http://imageshack.us/photo/my-images/215/dsc01024m.jpg/

Also, if I continue making tests in furmark, is it possible to burn video card?

Thank you