If I want to keep DDR2 Ram & 8800GT Video card when upgrading from Core2Duo to i5/i7, which motherboard is the best? Can we use RAMS with different speeds on a Motherboard?
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Hello,Â
 If you’re planning to upgrade to the iSeries (i3/i5/i7) which could either be the LGA 1156 or LGA 1366 you all have to upgrade to DDR3 since these CPUs only support this type of RAM. Your older CPU uses the LGA 775 which is inherently DDR2. I'm sorry to say that but that is usually the case when it comes to new hardware, it is not backwards compatible. But you shouldn't worry DDR3 is now actually cheaper than DDR2 because of the supply so upgrading shouldn't be too much of a problem.Â
 The video card you can keep without any problem. Just make sure you also have a good power supply to guarantee that your system will run stably.
 Also you can use RAMs with different speeds but it will always default to the lowest speed. For example you have a 1066MHz and a 1333MHz ram, both will run at 1066MHz.
Hope this helps,
Howard Taft
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That’s right. An Intel Core i5 or Intel Core i7 processor supports DDR3 and later RAM module types. You probably can use your graphics adapter if you are planning to upgrade your system if the new motherboard you’ll be using supports its interface. The majority of the newer motherboards nowadays support both PCI and PCI Express slots so you probably won’t have a problem installing your graphics adapter.
But the problem is with your RAM modules. You will probably have to replace it with a DDR3 type because motherboards that support Intel Core i5 and Intel Core i7 processors support DDR3. Also, there is no problem using RAM modules with different speeds. As long as they are compatible, they will work. The problem is the speed.
When you combine memory cards with different speeds, the fastest memory card will take the speed of the slowest memory card. This means, your slowest memory card will drag the entire speed of your memory down to its fastest supported speed. For example, you have you two RAM modules with speeds 166 MHz and 200 MHz.
When they operate, the memory card with 200 MHz speed will be dragged down to 166 MHz putting your entire memory speed to only 166 MHz. That’s the disadvantage. Using RAM modules with varying speeds degrades the performance of the memory dragging it down to the speed of the slowest RAM module.
