512MB GeForce 8400 GS (EVGA) OC

I got my 512MB GeForce 8400 GS (EVGA) Over Clocked way over clocked maxed out And it was getting kinda HOT it was above 160F So what i had to do is i Took out the Video card And took the Fan Off then i Wiped off the Thermal Paste.And Replaced it with Arctic Cooling MX-4 works well i use the same stuff on my CPU's And my CPU's Stay around a cool 85F even on high demand.Ive been Playing some GTA4 witch is a very Demanding game for the Video cards.My temp was above 160F while playing GTA4 But now its Below 160F but Speccy is saying its under 155F witch is Good.I am using MSI AfterBurner too Over clock works well.

My Factory sets are
Core Clock 567MHZ
Shader Clock 1400MHZ
Memory Clock 400MHZ

But i can Over Clock it too Max witch is.
Core Clock 740MHZ
Shader Clock 1820MHZ
Memory Clock 520MHZ

What would you guys think the best setting would be.

 

Can Constant Voltage Make video card heat up

 

Is it better too have Fans that You Can Adjust there Speed through the Bios

These Fans Connect to the MOB three pins
http://www.newegg.com/Product/Product.aspx?Item=N82E16835103052

But these won's Connect too the White connectors from the Power Supply 4pins
http://www.newegg.com/Product/Product.aspx?Item=N82E16835104003

Witch are better to have MOB connection or Power supply wons

 

Im kinda looking toward a heat sink for my video card if any body has suggestions let me know.I can provide a link too my video card too Show you witch i have.