Pentium 4 processor runs very slowly

Both frequencies are being correctly reported, because the Intel D850MV motherboard does not support a 533MHz Front Side Bus (FSB) speed.

The so-called 533MHz FSB speed of motherboards that support it is only the base FSB of 133MHz multiplied by 4 to express the effective FSB speed of the RAM, which is not a frequency. It is the effective speed (frequency) of the RAM using DDR RAM and DDR RAM operating in dual-channel mode. The RAM would be running at an effective speed/frequency of 133 X 2 = 266MHz using Double-Data-Rate (DDR) RAM, which functions at double the data rate of the FSB.

Ordinary DDR RAM working in dual-channel mode, which must be supported by the motherboard (also the processor with the AMD Athlon 64 FX processors which have onboard memory controllers), effectively doubles the DDR speed, making an effective FSB in this mode of 133 X 4 = 533MHz..

However, this particular Intel motherboard only uses a base FSB of 100MHz, and so cannot go any higher than an effective dual-channel DDR "FSB" of 400MHz (4 X 100). Therefore, with the RAM running at an effective speed of 400MHz, with a clock-multiplier setting of 17x, the 2.26GHz Pentium 4 processor runs at only 1.7GHz (17X100), because the maximum frequency is the product of the base FSB multiplied by the clock-multiplier setting.

The 533MHz "FSB" (133 X 4) has a base FSB of 133MHz, so multiply 133 by the 17x multiplier and you get the 2.26GHz of the Pentium 4 processor. Before you purchase a processor upgrade, you must know exactly what base FSB and clock-multiplier settings the motherboard provides.

Note that even if the motherboard provides the required settings to run a particular processor, it might require a BIOS reflash in order to be

recognised by the BIOS, because the BIOS programmers might not have given the BIOS the ability to recognise that particular processor as it had not been issued when the BIOS was created.

The processors and motherboards that run RAM memory at an effective speed of 400MHz and

533MHz are of different architectures, so no BIOS update will make it possible to run this P4 processor at its full speed on your Intel D850MV motherboard.

If the motherboard provided the 26x clock-multiplier setting required, you could make a 2.6GHz Pentium 4 that operates at the 100/400MHz FSB speed run at full speed, but not a 133/533MHz model of the Pentium 4. However, the Intel D850MV motherboard doesn't provide a 26x setting, only a maximum setting of 17x, so 1.7GHz is the maximum frequency that the processor can run at on this motherboard.

In this case, being ignorant of the processor's requirements resulted in the purchase of the wrong model Pentium 4. If this was a case of being sold the wrong processor after specifically identifying which board was in use to the seller, then the fault obviously lies with the vendor company, as the salesperson should have been able to find out which Intel processors can run on that particular Intel motherboard.