Adding PC2100 Ram to PC2700

  F1Chris 17:42 15 Aug 2005

I have a single 512mb PC2700DDR RAM installed in an Intel D865PERL Motherboard with a P4 2.66Ghz processor.

I've been given 2x 256mb PC2100 RAM chips.

I think my mb can take them and understand everything will run at the lower speed once they're installed.

My question is. Am I better off performance wise with 1024mb of PC2100 or sticking with just the 512mb of PC2700?

I don't know if the following is relevant or correct. SiSoft Sandra says FSB is 4x133mhz and Memory Bus Speed is 2x166mhz.

  ACOLYTE 17:56 15 Aug 2005

If it were me i would leave the gig of PC2100 in,unless you buy another 512 of PC2700,i dont see a point in losing 512 just cos the other ram is faster.

  Joe R 18:22 15 Aug 2005


As acolyte states, you would be better using the full Gb of ram.

You will though, need to change the memory bus speed to 133.

  Totally-braindead 18:39 15 Aug 2005

I honestly haven't a clue, how about trying it for a week with different types of programs and then change it and run the same programs again and see if you notice any difference.

  F1Chris 19:02 15 Aug 2005

Thanks for the replies. I was set to just give it a go and see what happened. I assumed the Memory Bus Speed would adjust automatically.

I've had a look in BIOS and it's greyed out, I can't access it to change. I'm wondering if it'll allow me to set something different once the RAM is installed as it'll detect the change? I'd rather know before I do anything than risk knackering the slower RAM

  Joe R 19:03 15 Aug 2005


it won't knacker the ram, but with the fsb set at 166, it may not recognize it.

  dan11 19:40 15 Aug 2005

What was the setting, in the bios.

Advanced > chipset configuration > sdram frequency?

Or did you just try the main menu?

I had a spare 512Mb pc2100 dimm, I added it to my 512Mb pc2700 dimm. Yes, they both run at 133Mhz, but the machine is a hell of a lot faster with the extra ram:-))

  F1Chris 19:51 15 Aug 2005

SDRAM Freq was set to Auto. I'm going to give it a go now and try installing. I've done a couple of benchmark tests so I'll see if I get a speed increase.

  F1Chris 20:18 15 Aug 2005

Well, it's been added. BIOS automatically adjusted the speed to 133Mhz. The memory bandwidth benchmark tests I did show that things are running slower but maybe double the RAM compensates, time will tell. I'll judge perfomance on how the system feels, not what the figures say.

I'm running Single Channel rather than Dual Channel, am I right in thinking I'm stuck with that because of the different RAM and I can't improve things by moving them into different sockets?

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