Will running an A64 with PC2100 RAM slow it down much?

[LiekOMG]

I have 1gb of PC2100 and i'd rather not put it to waste. Would there be much slowdown in games if I used this PC2100 over the PC3200 thats supposed to be used in an Athlon64 3000+ system?

Either way, I assume it'll be much faster than the AthlonXP 1600 that it'll be replacing.

 

[Peter]

Not much ... thanks to the FSB-less direct connect architecture, there is no inherent extra penalty in using RAM that doesn't sync up to the (nonexistant) FSB.

A64 has excellent caching algorithms, so application/game speed loss from slower DRAM is not actually as much as raw RAM throughput benchmarks suggest.

Now, Athlon64 3000+. If that's a socket-939 system, that's an 1800 MHz processor. Your PC2100 RAM will be run at CPU/14 ratio, or 128 MHz, down five from the rated 133 MHz. That's close enough.

Mind that you'll need a pair of /identical/ DIMMs for socket-939 use.

 

[LiekOMG]

Its socket 754 A64. That won't pose a problem correct?

 

[l Thomas l]

Sorry to hijack your thread. -_-

Originally posted by: PeterMind that you'll need a pair of /identical/ DIMMs for socket-939 use.

Oh wow I never knew that. I thought that was just for better performance. So my crappy stock dell and rosewill DDR SDRAM sticks won't work?

Stock dell is 512mb PC2100 (133mhz)
Stock rosewill is 512mb PC3200 (200mhz)

Man. I guess I could just use 512mb for a while but I'd definitely want to upgrade eventually.

 

[Heidfirst]

Originally posted by: LiekOMG
Its socket 754 A64. That won't pose a problem correct?

more than it would on an S939 system in dual channel (754 is single channel only).
With a dual channel system the CPU would probably still have got enough bandwidth but on 754 it's probably going to provide a bottleneck - once upon a time I tested PC2700 v P3200 on a 754 & it lost about 10% performance so with PC2100 I would expect to lose more.
As you say though it should still be an improvement over an Athlon XP (but PC3200 is cheap).

 

[Peter]

Originally posted by: LiekOMG
Its socket 754 A64. That won't pose a problem correct?

Nope, no problem there either. Only the speed loss will be a bit more prominent than on S939.

 

[aka1nas]

Originally posted by: l Thomas l
Sorry to hijack your thread. -_-

Originally posted by: PeterMind that you'll need a pair of /identical/ DIMMs for socket-939 use.

Oh wow I never knew that. I thought that was just for better performance. So my crappy stock dell and rosewill DDR SDRAM sticks won't work?

Stock dell is 512mb PC2100 (133mhz)
Stock rosewill is 512mb PC3200 (200mhz)

Man. I guess I could just use 512mb for a while but I'd definitely want to upgrade eventually.

You would have to either run them at the lowest speed or try OC'ing the slower stick for it to work in dual channel. Running 2 sticks in single-channel is hit-or-miss with socket 939 boards. IME, some handle it fine, others freak out.

If the slower stick can handle PC2700 speeds you could run them both at that with loose timings and it wouldn't absolutelty ruin your performance. You would lose ~10-15% IIRC.

 

[l Thomas l]

How do you test if it'll handle that much? Is booting up enough? Or would I have to run a memtest? I never could get those memtests to run.

Also, would it be better to run them in dual channel at the same low speed, or run them both in single channel?

 

[aka1nas]

Probably dual channel would be preferable. I would see if you can get memtest 86+ to run without errors as well. Or at least get it into windows and run Prime95.

 

[Peter]

Originally posted by: l Thomas l
Sorry to hijack your thread. -_-

Originally posted by: PeterMind that you'll need a pair of /identical/ DIMMs for socket-939 use.

Oh wow I never knew that. I thought that was just for better performance. So my crappy stock dell and rosewill DDR SDRAM sticks won't work?

Stock dell is 512mb PC2100 (133mhz)
Stock rosewill is 512mb PC3200 (200mhz)

Man. I guess I could just use 512mb for a while but I'd definitely want to upgrade eventually.

Question isn't so much, are they identical in speed, but are they identical in /organization/. If they're both single-sided or both double-sided, a halfway intelligent BIOS will set them up for 133 MHz dual-channel operation alright. If they're made from differing /types/ of chips not just differing speed grades, dual-channel won't work.

 

[l Thomas l]

Originally posted by: Peter
Question isn't so much, are they identical in speed, but are they identical in /organization/. If they're both single-sided or both double-sided, a halfway intelligent BIOS will set them up for 133 MHz dual-channel operation alright. If they're made from differing /types/ of chips not just differing speed grades, dual-channel won't work.

Oh yeah, they are identical in appearance. They're not those double sided double stacked ones or anything. Haha I just got some double sided, double stacked RAM that's only 64MB.