jonrice

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 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

Cromewell

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.

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jonrice

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

Burgerbob

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.

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StrangleHold

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

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PC eye

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.

StrangleHold

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!

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NZXT Apollo
S75QB 750W
ZEROtherm FZ120
Phenom II 720BE (X4) 3.5GHZ.
Gigabyte GA MA790X UD4P
G Skill DDR2 1066 4GB.
MSI GTS 250
Seagate 7200.12 500GB.

Welcome to the show

PC eye

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

jonrice

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...

StrangleHold

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.

__________________
NZXT Apollo
S75QB 750W
ZEROtherm FZ120
Phenom II 720BE (X4) 3.5GHZ.
Gigabyte GA MA790X UD4P
G Skill DDR2 1066 4GB.
MSI GTS 250
Seagate 7200.12 500GB.

Welcome to the show