memory not running at 266mhz

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jonrice

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Hello, little problem my board takes PC2100 memory I puchased a new stick of 512mb which is surposed to run at 266mhz but its running at 133mhz could this be down to my bios being pritty old, I have checked the bios and theres no setting for 266mhz only 133mhz....or have I been ripped off:mad: I have also run a system check, one that tells you the cpu speed and ram size, speed ect...any ideas...my boards and old epox from 2002 and Ive never updated the bios any thought

cheers jon
 
PC2100 is 133MHz DDR memory. So that means it runs at an effective rate of 266MHz. If you bought PC2100, it wouldn't fit in a PC133 (133MHz SDR) slot so you probably didn't get ripped off.
 
I see, the hole things a little confuseing for me to be honest I have read up on it but it ant going in,.....

From what I understand PC2100 comes in 133mhz and 266mhz and you can not or should not mix the two.

My old stick of ram was running at 133mhz, so I assumed when buying a stick of PC2100 266mhz it would run at 266mhz.

I guess I need to do some more reading.

cheers
 
If you have just one stick of slower RAM with some faster stuff, it automatically runs as slow as the slowest clocked RAM. You would have to get all 266MHz RAM (and probably a new mobo) to have it all at 266MHz.
 
PC2100 runs at 133mhz, they say 266 because of it being DDR. 133X2=266mhz. Old ram thats not DDR could only read or write one way at a time. DDR can read and write at the same time. So its 133mhz both ways=133X2=266
 
The main reason for seeing 133mhz is dividing dual channel in half. In other words a 266mhz is 133mhz x 2 = 266mhz total. A DDR400 board sees 200mhz as the top setting in the bios. Lowered to 166mhz in the bios means 333mhz total. If your cpu runs at a speed lower then the max fsb speed then the fsb is automatically lowered. On a 400mhz board(200 x 2) running 266mhz PC2100 memory will slow an Atholon XP3200 400mhz cpu down to 266mhz.
 
I see that makes sense, I got confused due to buying it of ebay some adds said 133mhz and some 266mhz so I assumed my new ram would run at 266mhz. so my old stick of ram will be fine as that was running at 133mhz...

So the max speed for PC2100 memory IS 133mhz x 2 and thats the speed I will see in the bios 133mhz....

yep...
 
Right, but now some bios do the same, some call it 266 and some 133, but if its PC2100 its DDR 266. Plus PC133 and PC2100 wont even fit in the same kind of slot anyway.
 
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PC 2100 runs at 133MHz. It's advertised as running at 266MHz simply because the memory chips can transfer 2 bits per clock instead of 1 bit per clock (DDR2 transfer 4 bits per clock). So, effective speed is 266MHz.
 
StrangleHold said:
What! The way DDR ram works and Dual Channel has nothing to do with each other. DDR is DDR even if your not running a Dual Channel board!
Click to expand...

Dual inline memory module with the equivalent of two channels! Dimms have a 64bit data path while the older simms have the 32bit. It's also referred to as Double data rate syncronous dynamic ram. Now multiply the following by 2 for the advertised total.

DDR-200: DDR-SDRAM memory chips specified to operate at 100 MHz
DDR-266: DDR-SDRAM memory chips specified to operate at 133 MHz
DDR-333: DDR-SDRAM memory chips specified to operate at 166 MHz
DDR-400: DDR-SDRAM memory chips specified to operate at 200 MHz
 
Still has nothing to do with Dual Channel, Dual Data Rate Ram and Dual Channel on a motherboard is not the same thing.
 
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Dual inline memory module with the equivalent of two channels! Dimms have a 64bit data path while the older simms have the 32bit. It's also referred to as Double data rate syncronous dynamic ram. Now multiply the following by 2 for the advertised total.
Click to expand...
SIMMs also had to be installed in pairs, but PC133 (if that was what was bought, which by all appearances, it isn't) isn't a SIMM and it's not DDR either.
 
He has PC2100-DDR266 and it was showing as running at 133mhz and I was telling him that was right, some bios show it as 133 some show it at 266. PC eye starting talking about simms ram and Dual Channel, either has nothing to do with anything?
 
Oh I agree completely with you, I was just trying to figure out how SIMMs made it in here when everything was taken care of by post 5 (your first post here).

I wasn't going to, but the more I think about it the more I think this one should be put to bed.
 
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