The latest models of the Intel Celeron and Intel Pentium 4 use the LGA775 (also known as socket T) socket. The dual-core version of the Intel Pentium 4; the Intel Pentium D also fits into the same socket. To make things worse: Intel Core 2 Duo and Intel Core 2 Quad processors fit too!
All this can be confusing when upgrading or buying a new system. This article will explore the LGA775 socket and it’s possibilities.
Important!: Always check the product page of your boards manufacturer for compatibility!
What defines whether CPU x does run in LGA775 or not?
1. The chipset
2. The BIOS
3. The VRD
Important!: If one of these three factors are not applicable with your hardware the processor won’t be supported. Example: If your i915-based motherboard does support VRD10.1 and the BIOS supports the Intel Pentium D processor, the Intel Pentium D processor won’t work since the chipset is the limiting factor.
The chipset on the motherboard is one of the three parts. Down below a short list of chipsets used on LGA775 boards with a LGA775 socket
|i865 / i875||This chipset is rather old. Is able to run with the Intel Celeron, Intel Pentium 4, Intel Pentium D and Intel Core 2 Duo if the other two factors are positive.|
|i915||This chipset is quite limited since it doesn’t support dual-core processors. That means only the Intel Celeron and Intel Pentium 4 are supported.|
|i925||Intel Celeron, Intel Pentium 4.|
|i945||Intel Celeron, Intel Pentium 4, Intel Pentium D (but not the D840 EE) and Intel Core 2 Duo|
|i955||Intel Celeron, Intel Pentium 4, Intel Pentium D and Intel Core 2 Duo|
|i965||Intel Celeron, Intel Pentium 4, Intel Pentium D, Intel Core 2 Duo and Intel Core 2 Quad.|
|i975||Intel Celeron, Intel Pentium 4, Intel Pentium D, Intel Core 2 Duo and Intel Core 2 Quad.|
|nForce4||Intel Celeron, Intel Pentium 4, Intel Pentium D (but not the D820), Intel Core 2 Duo.|
The BIOS must be able to recognize the CPU. To check whether your BIOS is compatible with a specific processor please take a look at the product page of the manufacturer of your board since it's not possible to tell exactly which processor will run.
Basically and not always applicable: If your board supports a processor it's likely faster/slower processors will be supported too. But, watch out you're dealing with the same exact version (stepping).
Example: Four different versions of the 3GHz Intel Pentium 4 (Intel Pentium 4 530). The Intel Pentium 4 531 even exists in two models, the E0 and the G1.
VRD stands for Voltage Regulation Down. In easy words this third part will be about delivering the correct voltage to your processor.
Basically I will discuss VRD10.1 and VRD11. The last one is required to run Intel Core 2 Duo processors. If your board (like the Intel D975X Rev. 0302 ‘Bad Axe’) does meet the first two requirements but doesn’t have the correct VRD version the CPU won’t run. Even if the BIOS will allow you to correct voltage settings manually!
VRD10.1 is needed for processors like the Intel Celeron, Intel Pentium 4 and Intel Pentium D. VRD11 is the minimum for Intel Core 2 processors. Of course it's backwards compatible which means that the 'VRD10.1'-processors will run with VRD11 too.
What is the difference between VRD10.1 and VRD11?
Both VRD10.1 and VRD11 are able to deliver voltages between 0.8375V and 1,6V. The big difference (which is actually small) can be seen in the steps between the voltages. VRD10.1 can take steps of 12.5mV. VRD11 is able to take smaller steps, namely 6.25mV.
Always check the product page of the manufacturer of your board. If you can't find a list of supported processors it's hard to tell whether a processor will function or not. If you can't find a list of supported processors check out if the chipset is compatible and search for information on the Internet. If you see someone on the Internet running an Intel Core 2 Duo E6300 you can be pretty sure an Intel Core 2 Duo E6400, E6600 and E6700 will run too as they are technically pretty much the same. Still be careful to check the technical specifications and be sure the FSB and stepping are the same.