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what memory for FSB 800 CPU and 400/533 Motherboard?

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August 27, 2007 9:55:28 AM

Hi!

I have a Motherboard that supports 400/533 MHz RAM, and an Intel Dual Core 2x2.4 GHz CPU with FSB of 800 MHz. What memory should I use? 400 or 533? Is there any performance loss involved when 533 RAM downclocks to 400?

Thanks!

Sincerely,

Bojan Hrnkas
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August 27, 2007 11:12:17 AM

1st guess is that you would want the 533 DDR2 Ram (I'm assuming it's DDR2 compatable). What is the Motherboard that you have? Make and model please.
August 27, 2007 3:13:39 PM

Yes, it is DDR2 compatible. It is a rare HP/Compaq OEM Motherboard. Is my system gonna be faster with 533MHz DDR2 than with 400MHz DDR2, even though FSB ist 800MHz?
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August 28, 2007 2:05:07 AM

I'm not a memory master by any means, so I'm not sure if that would help your speed. I know the 800mHz FSB is usually related to the CPU's capabilities, but is also related to the whole system. I just don't know enough to help you with that question. Hopefully someone else can help you there.
August 29, 2007 3:04:32 AM

Im running my 800mhz fsb p4 with 1:1 timming on my ram. I achive this though pc3200 or ddr @400mhz with timmings of 2.5-3-3-8.


D'oh! Saw the ddr2...

The ddr 533 will downclock to 400 mhz, you could probally get better timings too. Is it pc6400 or ddr2 with 400mhz effecive ( I dont think that exists) the ddr2 @ 400mhz is actully running at 800mhz wiile your 533 will run at 1066mhz. You should probally try to run your cpu and ram 1:1. Im not shure how to achive that with a pentium d but with a core 2 duo it would run ddr2 400mhz/800 effective with timmings of 4-4-4-12. If your using a core 2 duo, then get pc 6400 with the timings i just mentioned.
August 29, 2007 4:28:01 AM

Quote:
You should probally try to run your cpu and ram 1:1


He's got a HP oem board, those things are locked up pretty tight in the BIOS. If your cpu is running at 800mhz fsb, this means that it is 'quad-pumping' a 200mhz system bus (4x200). The ram, being Double Data Rate (DDR2), doubles this bus to run at 400mhz. Even if you have 533mhz ram, the system will still only use it at 400mhz unless you overclock the system bus. But I'm guessing that there are no adjustments in BIOS, right?

I would go for the 533 (or higher, there wasn't much difference in cost the last time I looked) ram so you can use it on your next, and hopefully clockable, system:) 
a b } Memory
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August 29, 2007 4:49:58 AM

Maybe at least 667mHz for the next build. Do you think that the memory would still work for his setup if he used 667?
August 29, 2007 5:02:52 AM

You won't notice any difference at all. I had my old P4 3.0GHz and put 533 in and got 100 points on 3Dmark05, thats hardly a diff. I wasited my $$$.
August 29, 2007 10:51:25 AM

Thank you guys! It pretty much solved my dilema. I think I am going for 400MHz RAM, since my next system will deffinitely gonna make use of faster RAM than 533.
!