1333mhz FSB cpu in a 1066mhz FSB mobo?

[EarpWJ]

I have a Asus P5B motherboard, the max FSB on it is 1066mhz. I want to upgrade the processor to a Q9550(2.83ghz) which has a 1333mhz FSB.

I assume the motherboard would underclock the CPU to a 1066mhz FSB right? What would the end result be in effective ghz?

 

[hunter315]

It would end up running at about 2.26GHz, assuming the BIOS even has support for it, it might not. Check that first.

 

[EarpWJ]

Thanks Hunter, how did/do you calculate that?

The BIOS supports it with a beta driver...

For gaming would I be better off with a core2duo E7500 (2.93ghz) or using the core2quad Q9550 @ 1066mhz FSB?



I do plan on upgrading again of course, but for the next half year + I am not going to have much more than the ~$250 a Q9550 would cost to spend on my comp.

 

[hunter315]

The FSB is 4x the base clock speed, so a 1333MHz bus is 333MHz base clock, 1066MHz is 266MHz base clock. The CPU speed is its multiplier times the baseclock, 2.83GHz/333MHz=8.5 is the multiplier for a Q9550, multiple 266MHz by 8.5 and you get about 2.26GHz.

 

[dEAne]

I have used this mobo for overclocking session - I have read the manuals and reviews but I didn't accomplish what we want.

http://www.hardwaresecrets.com/article/408

http://www.anandtech.com/show/2070/4

 

[EarpWJ]

The FSB is 4x the base clock speed, so a 1333MHz bus is 333MHz base clock, 1066MHz is 266MHz base clock. The CPU speed is its multiplier times the baseclock, 2.83GHz/333MHz=8.5 is the multiplier for a Q9550, multiple 266MHz by 8.5 and you get about 2.26GHz.

I have been running the core2duo6400 on the p5b at 8 x 350 (2.8ghz) so that puts my current FSB at 1400 right? So IF the bios update works I should have no problems running the Q9550 right?

 

[iam2thecrowe]

I dont thing running the 9550 is worth it, especially not underclocked. Its an expensive CPU to use if it doesnt work properly. If you really want quad core get a q6600 or something similar off ebay, they can also be overclocked quite a bit. If you are using this PC for gaming, the e7600 would give you enough power to run any game.

http://www.anandtech.com/bench/Product/53?vs=87

 

[jitpublisher]

If the BIOS doesn't recognize the processor, the board may refuse to even POST.
Since the board was never meant to run that processor in the first place, the BIOS is definitely not going to identify it. The odds are against what you are trying to do ever working at all, let alone at a slower speed than it's supposed to be.

In short, this is a really bad idea. Change your line of reasoning or be prepared to be disappointed, and poorer.

 

[rwpritchett]

I might be a little late to the party, but to the OP:

Yes, the P5B can run 1333FSB processor's just fine. I've been running a Q9650 on mine for a few years.

 

[Mehdi K]

there should be no problem with the compatibility and FSB ratings . better to use the CPU without FSB parity,, Like Q9400 ,, as i'm using 8 GB of 800 MHZ ram on P5b-v . if a CPU with FSB parity like Q9550 is used then The ram would run at 667 MHZ !..

 

[LeGeNdSChAoS]

I might be a little late to the party, but to the OP:

Yes, the P5B can run 1333FSB processor's just fine. I've been running a Q9650 on mine for a few years.

there should be no problem with the compatibility and FSB ratings . better to use the CPU without FSB parity,, Like Q9400 ,, as i'm using 8 GB of 800 MHZ ram on P5b-v . if a CPU with FSB parity like Q9550 is used then The ram would run at 667 MHZ !..

But have you overclocked the FSB (even if you can) to closer to 1333mhz? Because i just bought this board without noticing the max 1066 fsb.. and i got e5450 which is 1333 fsb.. can i do something about it so i can at least run it at stock 3ghz because now its at 2.2ghz