# [SOLVED] Use an 800 fsb CPU in a 533 mobo?



## renaw (Jun 19, 2008)

What would happen if I plugged a salvaged 2.8 ghz northwood Pentium4 with an 800 mhz bus speed into an MSI motherboard only rated for 533 mhz fsb?

Could it damage something? Is it possible that it would work? I assume it would run a lot slower than 2.8 ghz if it runs at all.


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## Pharaohz (May 10, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

check the motherboard manual and it should list the fsb it can allow. Though I would guess you would be fine. 800/533/400 are most often found for options for cpus on mobos.


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## renaw (Jun 19, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

It doesn't support fsb 800.


renaw said:


> an MSI motherboard only rated for 533 mhz fsb


 I meant 533 max. It also supports 400.

What I'm wondering is exactly what that FSB rating means. I know that a CPU can be run at a different clock rate than what it's designed for. But can it run at a different bus speed? Will this 800 fsb processor just run slower than it's supposed to, or will it not run at all, or -- most importantly -- will I cause some damage by trying it? Does anyone know?


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## vladimirb (Mar 31, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

Hey mate,
It could be long to explain so go here and read all about it ^-^
http://en.wikipedia.org/wiki/Front_side_bus


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## renaw (Jun 19, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

Thanks, Vladimir. A very interesting article. Nothing about unsupported CPU's though.

It has a comment about FSB in the section on overclocking:


Wikipedia said:


> For all processors, increasing the FSB speed can be done to boost processing speed.


 But it doesn't say how to increase (and decrease?) the FSB speed.

The only thing it says about possible damage is a warning about the practice of overclocking in general:


Wikipedia said:


> This practice pushes components beyond their specifications and may cause erratic behaviour, overheating or premature failure.


That whole section sounds like it's only talking about increasing the speed of a supported CPU. It doesn't say anything about using a CPU that the motherboard manufacturer says is not supported. That's what I'm interested in. I already have the processor, and I'd like to try it and see if it will work at all. But I don't want to damage the board or the processor.


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## Tumbleweed36 (May 14, 2005)

*Re: Use an 800 fsb CPU in a 533 mobo?*

If the FSB speed is not supported, it would most likely not work.


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## renaw (Jun 19, 2008)

*Damaging a motherboard?*

I guess I got off to a bad start with the original title of this thread. What I'm really asking about is how fragile motherboards are.

If I have a CPU that fits the socket, and it operates at the right voltage, only it's not supported because of its FSB speed, will I do any damage by plugging it in to see what happens? If it runs slow or doesn't run at all, that's fine. I'm just experimenting. But I don't want to do it if it might make something burn out.

I've always been worried about damaging a motherboard, but I'm starting to think they're pretty tough. I accidentally touched a probe to two pins at once and got a nasty spark and burning smell, but everything still worked fine after that.

And I misunderstood the directions on a CPU cooler and installed it rigidly hanging above the CPU, no contact at all. The system kept shutting down, and in my stupor I thought it was because of the speed control on the cooler's fan. So I took out the speed control and started up again. In the second or two between between when I got Everest's temperature sensor working and when I yanked the plug, the CPU temperature climbed from 110 to 118° C. But I got lucky again, and the CPU survived.


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## Xsoftware (Jun 13, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

I wouldn't reccomend putting the CPU into the mobo. You may cause serious damage to both the mobo and the cpu. But if you really wan't to, have a search on google to see if it might work.


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## Pharaohz (May 10, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

It should not work. And although it is more likely to just shut down after you hit the power, its not a good idea to find out. And heres another point. The motherboard isnt the only thing that has to accept it. The ram would have to be pc-3200 or it shouldnt work anyways. Best case is, it turns on and runs at 533fsb. Worst case, it goes boom and takes your mobo and maybe even your ram with it.

Now if your just tring to have some fun, post the results


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## renaw (Jun 19, 2008)

*Re: Use an 800 fsb CPU in a 533 mobo?*

Thanks for the advice! I'm not going to try it. I get enough excitement from accidentally almost burning things up. I don't need to do it on purpose, any more than I need to bunge-jump. I'll leave both of those to people who have the ordinary safety issues under control.


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## Tumbleweed36 (May 14, 2005)

Wise move on your part.


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