Joined: 29 Apr 2002 Posts: 0 Location: Tyne Valley
Posted: Mon Jan 06, 2003 12:00 pm Post subject: PC2700 DDR with 133fsb Athlon
I built my sister a PC a few months ago. She wanted the "latest stuff" so I stuck in some DDR which runs at 333mhz. The CPU was a 2000 Athlon with a 133 FSB (or is it 266?). Anyway, I'm sure I set the RAM to run at 333mhz in the BIOS, but I've just read that using 333mhz RAM with a 266FSB can be detrimental to performance. Should I swap the memory for 266 mhz stuff? Or have I picked this up wrong?
I'm pretty sure I didn't accidentally overclock the Athlon. It was running at 16-something mhz. The mobo is a GigabyteGA-7VRXP.
Also, is it correct that the latest Athlons have a FSB of 333mhz? Have these got a new name or are they still Athlon XP's?
Cheers.
Joined: 18 Apr 2002 Posts: 16777215 Location: Kuala Lumpur, Malaysia
Posted: Tue Jan 07, 2003 11:32 am Post subject:
The CPU natively uses a 133MHz FSB, which is 266 in Double Data Rate
terms, which I will continue to use in this post.
There is very little performance gain by using asynchronous 333 memory
bus with a 266 FSB. You might not notice the difference either way
except in some benchmarks,, leaving it at 333 or decreasing to sync
266 speed. If the system will remain stable by both lower the memory
bus to 266 AND decreasing the CAS setting to 2, you might reap a
little under 5% gain if it was previously running at CAS3, but usually
closer to 3%.
There is only one way to significantly increase the performance using
the same parts... unlock the CPU, then change the FSB speed to 166MHz
(333 DDR) and the multiplier to 10X (for spec'd MHz, or whatever you'd
like), then you'll have the memory bus back in synchronous mode at 333
DDR. Some people might consider this overclocking the CPU, but I've
never heard any reports of running a motherboard non-overclocked with
a processor at same total MHz speed, with memory stable, resulting in
any problems over the lower FSB speed... just as long as the
motherboard does drop the PCI divider to 1/5 at ~166MHz as I believe
yours does.
Joined: 29 Apr 2002 Posts: 0 Location: Tyne Valley
Posted: Tue Jan 07, 2003 12:10 pm Post subject:
Thanks Shaolin. My only concern is that her machine was under performing due to the type of memory. Evidently it's not, so I'm happy. Or...I would be if you hadn't sown that little "unlock" seed. I've got the same system, so I might try unlocking the CPU as you said. If I had the FSB and memory running at 333, would there be any extra work for the CPU to do? I'm thinking about the temp, which hovers around 57 at the moment. I don't want to start adding fans unless I have to.
Also...what does the "+" mean, in Athlon XP+ ? Is it something to do with it being locked? Is this the type of processor that you can unlock with a pencil?
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