raising fsb = no boot

intellisquid

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Hello all, new member and would-be OCer here. :)

My FSB and DRAM were both running fine at 166 mhz. I raised the DRAM clock to 200 mhz, which seems to work fine. But the FSB clock jumper only allows 133, 166 or 200 (While I think my CPU and mobo should both support 333). Setting it to 200 prevents WinXP from loading at all. I just get a blank screen after POST.
I think it's a bottleneck with my memory, but I want to check with you folks first before I upgrade anything. Setup:
MSI KM400-A
Athlon XP 2600+
512 MB Kingston PC2100, DDR SDRAM

On the CPU, I'm not sure if I have the 333 bus version or not. Is there a way to find out? CPU-Z reports my 'Bus Speed' as 333, but says my FSB is 166. How are these two different?
And on the RAM, the model number says it's 266. CPU-Z reports it as PC2100/133 mhz, because it's DDR I guess? However the BIOS only allows 200 mhz, not 266 for some reason. This is all pretty confusing. :|
Would anyone like to graciously clear this up for me?
 

c0d1f1ed

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PC2100 memory is intended to run at 133 MHz. So 166 MHz is already a high overclock. It's amazing you can even boot at 200 MHz. So stick to the 166 MHz it's the best you can get out of that system. Upgrading is not worth the money, unless you buy a whole new Athlon 64 system.
 

khha4113

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CPU-Z reports my 'Bus Speed' as 333, but says my FSB is 166. How are these two different?
166MHzx2=333MHz, DDR (Double-data-rate). However, your RAM PC2100 only supports 133MHz (or DDR266), so basically, set your RAM at 166MHz (or DDR333) is overclocking it.

:smile: Good or Bad have no meaning at all, depends on what your point of view is.
 

intellisquid

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Thanks guys, this is helping very much. For an upgrade, PC3200 seems pretty cheap(around $45), and goes up to 400 mhz. I would have to stop around 333 mhz if that's my CPU's 'advertised' FSB though, right? Do you guys think buying this RAM would be worth the performance increase?
 

intellisquid

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Yes, multiplier is locked as far as I know. The BIOS doesn't let you overclock the CPU, just DRAM and the FSB jumper. The board changes the CPU speed based on what FSB you select, but you can't directly change the speed. <P ID="edit"><FONT SIZE=-1><EM>Edited by intellisquid on 01/29/05 06:53 PM.</EM></FONT></P>
 

endyen

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no, actually your chips is suposed to run at an fsb of 166. If your current ram is okay at that speed, stay with it.
If you want to overclock, you have to raise the fsb above 166. There is no hope at all your computer wood be able to boot at 333. You would need an xp5000+ to do that.
 

intellisquid

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Even if I can't get 333, I would still like to get better than 166. Would upgrading the memory to something faster, like PC3200, let me raise the FSB any at all?
 

jammydodger

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166 is 333. DDR stands for double data rate. What it means is it sends twice the ammount of data for everyclock cycle than single data rate ram would.
i.e. 133Mhz SDRAM can send 1,064MB/sec
while 133Mhz DDR-RAM 2,100MB/sec twice the ammount (which is why they name it PC2100). Even though its still only running at 133mhz has twice the bandwith to SDR so they stated saying i was 266Mhz so people would know it is better than 133Mhz SD ram.

With a multiplier locked CPU, any raise to the FSB also increases the speed of the CPU, PCI bus, RAM and AGP bus (unless you have an AGP/PCI lock). My 2.6Ghz P4 increases speed my 13Mhz everytime I increase the FSB by one Mhz.

PC3200 RAM will allow you to overclock more, but your motherboard, CPU add-in cards and hard drives need to be able to handle it aswell. You can get data-corruption when increasing the PCI-bus because the hard disks cannot take it.
 

intellisquid

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Thanks for your post!
My mobo lets me increase the FSB in 33 mhz steps, up to 200, which is where XP quits loading. I think I'll get the ram and see if that fixes it, because I'm apparently pushing my current ram to the limit. Would you do this upgrade if you were in my shoes?

I think my other components should be able to handle 200 mhz, except maybe the hard drives. Is there a way to determine this or is it just trial and error?
 

jammydodger

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By increasing your FSB from 166Mhz-200Mhz you will be overclocking your CPU to 3200+ speeds. This is running your chip above the speed it was intended for, and can damage your hardware.
Your CPU may require a voltage increase or better cooling in order to reach those speeds.
You PCI-bus will be overclocked to 39Mhz which should pose a problem, however you might have display issues when overclocking your AGP bus to 78Mhz (supposed to be 66Mhz).
 

intellisquid

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The FSB selector in the BIOS is notched, and there's nothing about AGP/PCI divider selection. It's a terribly restrictive board. I think I'm going shopping for memory AND a motherboard now. :p will check out the Abit.
so if bus speed and fsb are the same thing, why are they reported differently? marketing? :eek:
 

fishmahn

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My 2600+ wouldn't run at 3200+ speeds (200fsb), but it would run at 195. However, I have a ultra-cheap PSU, and my mobo appears to undervolt my CPU (should be 1.65, shows steady 1.61).

If you set the jumper on the motherboard to 200, then that is setting the divider to /6 so that your AGP and PCI will be clocked correctly at 200.

There may be a clock speed adjustment in the BIOS (there was on my mobo), which adjusts the FSB clock in smaller increments than 33mhz. That adjustment also adjusts the speed of the PCI/AGP clock.

You'll definitely need faster ram to go up to 200, the PC2100 (as said before by others) is already overclocked at 166.

Mike.
 

intellisquid

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CPU-Z reports my bus speed at 333 mhz, and right below that, my FSB at 166. The terms 'bus speed' and 'fsb' mean the same thing though, correct? One is just reported to be twice as fast because of the DDR?
 

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