Questions about CPU compatibility in regards to FBS and TDP.

[drchristopher]

I am assuming that in the computer world a 4 year old computer should be called vintage, so I hope I am posting in the right spot.

I have a Dell Precision Workstation T5400, motherboard RW203, socket LGA 771, with a single Xeon X5450, FBS 1333MHz.

I am investigating upgrading the CPU to the most powerful one that will work. From what I have found so far, all the Dell processor options for this board have a FBS of 1333 MHz, but I don't want to just play it safe. I want to learn!

1) What happens (or maybe I should say- what doesn't happen?) if I replace the X5450 with a processor that has a FBS of 1600 MHz like a Xeon X5492?

2) If it will work, are there any advantages or disadvantages in using a processor with a faster FBS?

3) If it works, will it only work because processors, like RAM modules, are one step backwards compatible?

The voltage of these two processors is the same (0.85-1.35 V), but the TDP values are not. My X5450 is rated at 120W and the X5492 at 150W.

4) I assume that the voltage range is a set parameter of a given mobo (as I see it called in this forum) and that the voltage values of the CPU must fit within the mobo's CPU socket voltage ranges, but how much, if any, variance can be allowed?

5) Not just in my case, but in general, does the TDP value alone constrain what can be used or not and if so why?

6) I assume that it is safe to use a processor with a lower TDP, but if one with a higher TDP is used is the issue only making sure that the CPU cooling is adequate?

I know I posted a lot of questions here, thank you for you patience. Like I said, I want to learn! So I am not looking for a simple “It won't work.” or “It will work.” I would appreciate the what happens and why explanation.

Again, I want to, ahead of time, thank any and all of you for your greatly appreciated help!

[Tetrium]

Sorry for not answering your question directly, but I have no answer for it anyway.

A 4 year old computer isn't exactly vintage.
The definition of vintage hardware isn't set in stone and changing quickly as computer history matures.
Personally I'd call a computer older then 5 years 'old'.
A computer that's roughly 10 years old I'd call a retro rig perhaps.

Vintage for me is a computer where the motherboard is AT style instead of ATX style. usually the boundry is around 1997, give or take a year.

A computer that predates a 386 I just call antique and isn't really in my interest area.


I'd like to stress though, the definition of 'vintage hardware' is seen differently from person to person and changing rapidly in this time as computer history is still very young, and thus is aging MUCH more quickly then, say, architecture or art.


Edit: To answer a part of your question, there are many factors that determine what CPU will work in what motherboard. TDP is only 1 of them, but by no means a guarantee.

For instance, the Tualatin would often not work in many P3 motherboards, even though it's TDP was not higher.
Sometimes hardware is rigged into not taking anything more modern.

[gshv]

[drchristopher]

Thanks gshv!!
I learned the stuff I wanted to from your answers.
There is one thing that I did not understand though - "the processor will run at 3400 * 1333 / 1600 = 2833 Mhz." I understand the 1333, that's FBS of my X5450, the 1600 is the FBS of the X5492, but what is the significance of adding them together and where did the 3400 come from? 1333 + 1600 = 2933 or did you subtract 100 for some reason?
Thanks

[gshv]

It's not addition, it's multiplication:

3400 (X5492 core frequency) multiplied by 1333 MHz (frequency of your board), and divided by 1600 MHz (X5492 bus frequency).

Gennadiy