Underclocking Memory

[Stephan28]

Alright, I have a Barton 2500 on the way but I still have the Crucial 2100 memory. What are my options for using this memory on this system? Should I underclock the memory (.80 * 166 = 133) or just try running it at 166? Probably won't work huh?!!? Is that how this is done? I've never messed with Memory timings before? All I know is that the Barton runs at 333 FSB and the PC2100 is designed for 266 FSB. So I assume that I will have to change the speed of the memory to run slower. Opinions please:beer:

 

[Corporate Thug]

i dont think pc2100 will run @ pc2700

 

[Stephan28]

I didn't think so either so what do I do for the time being? Is my logic correct....underclock the memory bus to .8 * 166 for 133?

 

[bozo1]

What motherboard? Many let you run the memory and CPU at different speeds.

 

[Corporate Thug]

well, if you have an nforce 2 board, you can run it @ 133 *14 cuz nforce2 unlocks the chip. if not, you should be able to get the pc2100 to 150 mhz or so...

 

[Stephan28]

Yes, I have an 8RDA+ rev 1.1. So is this the better way of doing things lowering the CPU bus rather than the memory bus? Hadn't thought of that. Nice idea.

 

[Stephan28]

I was originally thinking to run the CPU at the rated speed and change the memory bus to a lower speed. I believe I can do this with this M/B. But which would be better? Slowing down the CPU bus or the Memory bus?!!?

 

[jatwell]

You know, most crucial pc2100 actually runs at 166, Cas 2.5 3-3-6

I've got 6 sticks that run 24/7 of Crucial PC2100 at 166 w/ the above settings and they work great.

What I'm saying is, you may be in luck Just give it a shot.

 

[KillaBong]

Crucial pc2100 is like the legendary overclocking pc2100. You may be unlucky, but I wouldn't doubt it does to 166 with the settings he suggested. I've even heard of people running this ram at 200mhz.

 

[AkumaX]

a lot of crucial pc2100 runs @ pc2700 speeds. the barton 2500+ has its PR rating determined by the higher fsb and extra cache. it is said to run on par of a theoretical t-bird @ 2.5ghz (or more closely on par to a p4). if an axp @ 2500+ were to exist on different platforms of the xp family, it would probably go something like this:

tbird 2500+ = 2.5ghz
xp 2500+ (133fsb) = 15.5 x 133
xp 2500+ (166fsb) = 12 x 166
barton 2500+ (166fsb) = 11 x 166
barton 2500+ (133fsb) = 11.5 x 133

btw all these assumptions are mine

 

[Jeff7181]

Definately run the RAM slower than the FSB if your RAM won't run at 166. In my experience with using RAM that's not rated as fast as I want to run my FSB, you get better performance from running the memory async if it allows you to run the FSB speed and in turn, the core clock speed higher. My nForce2 motherboard doesn't unlock multipliers above 12.5, so a multiplier of 14 wasn't an option. I bet if you keep your 166 FSB, and run your RAM at 80%, you'll get better performance than if you run your FSB and RAM both at 133... even if you adjust the mutliplier so it's the same clock speed.
The Athlon XP just isn't memory bandwidth hungry like the P4, so running things async doesn't create much of a bottleneck like it does with a P4. Athlon XP's benefit more from lower timings. And if you've got 2 sticks of RAM, run them in dual channel, with the lowest timings possible... and you'll have all the bandwidth available that the Athlon XP needs, and then some.

 

[rommelrommel]

Originally posted by: Jeff7181
Definately run the RAM slower than the FSB if your RAM won't run at 166. In my experience with using RAM that's not rated as fast as I want to run my FSB, you get better performance from running the memory async if it allows you to run the FSB speed and in turn, the core clock speed higher. My nForce2 motherboard doesn't unlock multipliers above 12.5, so a multiplier of 14 wasn't an option. I bet if you keep your 166 FSB, and run your RAM at 80%, you'll get better performance than if you run your FSB and RAM both at 133... even if you adjust the mutliplier so it's the same clock speed.
The Athlon XP just isn't memory bandwidth hungry like the P4, so running things async doesn't create much of a bottleneck like it does with a P4. Athlon XP's benefit more from lower timings. And if you've got 2 sticks of RAM, run them in dual channel, with the lowest timings possible... and you'll have all the bandwidth available that the Athlon XP needs, and then some.

Have you actually tried running any benchmarks with ram out of sync on a nforce2 board? It absolutely kills performance on the three different boards I've tried, asus A7N8X, epox 8RDA+, and Abit NF7-s.

 

[Jeff7181]

Originally posted by: rommelrommel

Originally posted by: Jeff7181
Definately run the RAM slower than the FSB if your RAM won't run at 166. In my experience with using RAM that's not rated as fast as I want to run my FSB, you get better performance from running the memory async if it allows you to run the FSB speed and in turn, the core clock speed higher. My nForce2 motherboard doesn't unlock multipliers above 12.5, so a multiplier of 14 wasn't an option. I bet if you keep your 166 FSB, and run your RAM at 80%, you'll get better performance than if you run your FSB and RAM both at 133... even if you adjust the mutliplier so it's the same clock speed.
The Athlon XP just isn't memory bandwidth hungry like the P4, so running things async doesn't create much of a bottleneck like it does with a P4. Athlon XP's benefit more from lower timings. And if you've got 2 sticks of RAM, run them in dual channel, with the lowest timings possible... and you'll have all the bandwidth available that the Athlon XP needs, and then some.

Have you actually tried running any benchmarks with ram out of sync on a nforce2 board? It absolutely kills performance on the three different boards I've tried, asus A7N8X, epox 8RDA+, and Abit NF7-s.

Yes I have, and no it didn't on mine. I ran my XP2500 @ 2210 Mhz (221x10) for a couple months until I got some PC3200 RAM. I ran a 221 Mhz FSB because my board and CPU could handle it, and I could run my PC2700 RAM at 75% so it would be at 166 Mhz. My memory benchmarks were lower of course, but as far as real world performance, I may have saw a 1-3% decrease in performance between that and my current setup.

 

[cow123]

Originally posted by: shady06
well, if you have an nforce 2 board, you can run it @ 133 *14 cuz nforce2 unlocks the chip. if not, you should be able to get the pc2100 to 150 mhz or so...

bah, i am so sick of you saying nforce2 boards unlock to high multipliers

the 8rda+ which he has will not... *not* go above 12.5 mult unless he mods the processor, no a bios update will not fix it, it's just a limitation of that board

 

[xSauronx]

Originally posted by: shady06
well, if you have an nforce 2 board, you can run it @ 133 *14 cuz nforce2 unlocks the chip. if not, you should be able to get the pc2100 to 150 mhz or so...

my hynix/spectek pc2100 was doing 175, and i think my mobo was the limitng factor there

try upping the fsb on it, if anything it wont work and youll have to just reset the bios (or hold INSERT when you boot up to restore the fsb settings)

 

[Stephan28]

the 8rda+ which he has will not... *not* go above 12.5 mult unless he mods the processor, no a bios update will not fix it, it's just a limitation of that board

I just checked my bios and I can adjust the FSB from 100 to 250 and the CPU clock from 3 to 24. It is an 8RDA+ Rev 1.1.:beer:

 

[Stephan28]

I've also been told that I should be able to pretty much set everything seperately on this board. In other words the PCI bus is locked (no need to worry there), the AGP bus is locked (I set it that way) and I can control the FSB and the memory speeds seperately.

Looks like I should be able to set the memory initially at "SPD" and set up the FSB to 166 (333) and boot up. Then I can play with the memory speed until I notice things are getting flakey?

What are the signs that you are pushing the memory too fast?:beer:

 

[Jeff7181]

Originally posted by: cow123

Originally posted by: shady06
well, if you have an nforce 2 board, you can run it @ 133 *14 cuz nforce2 unlocks the chip. if not, you should be able to get the pc2100 to 150 mhz or so...

bah, i am so sick of you saying nforce2 boards unlock to high multipliers

the 8rda+ which he has will not... *not* go above 12.5 mult unless he mods the processor, no a bios update will not fix it, it's just a limitation of that board

Yes it will. You're thinking of the Asus A7N8X Deluxe.

 

[Jeff7]

Originally posted by: Stephan28
I've also been told that I should be able to pretty much set everything seperately on this board. In other words the PCI bus is locked (no need to worry there), the AGP bus is locked (I set it that way) and I can control the FSB and the memory speeds seperately.

Looks like I should be able to set the memory initially at "SPD" and set up the FSB to 166 (333) and boot up. Then I can play with the memory speed until I notice things are getting flakey?

What are the signs that you are pushing the memory too fast?:beer:

If you set it to 166Mhz, Save and Exit from the BIOS, and it is able to reset and POST normally, well, it'll at least do that. Then you can test for stability using something like memtest86.
You'll know right away if it is incapable of 166MHz if it just freezes there, and/or starts beeping at you. Then, hit the reset button, and IMMEDIATELY start tapping the Insert key. This'll have the system boot at its default speeds - go into the BIOS and set the RAM back to 133MHz.

 

[Acanthus]

Originally posted by: Jeff7

Originally posted by: Stephan28
I've also been told that I should be able to pretty much set everything seperately on this board. In other words the PCI bus is locked (no need to worry there), the AGP bus is locked (I set it that way) and I can control the FSB and the memory speeds seperately.

Looks like I should be able to set the memory initially at "SPD" and set up the FSB to 166 (333) and boot up. Then I can play with the memory speed until I notice things are getting flakey?

What are the signs that you are pushing the memory too fast?:beer:

If you set it to 166Mhz, Save and Exit from the BIOS, and it is able to reset and POST normally, well, it'll at least do that. Then you can test for stability using something like memtest86.
You'll know right away if it is incapable of 166MHz if it just freezes there, and/or starts beeping at you. Then, hit the reset button, and IMMEDIATELY start tapping the Insert key. This'll have the system boot at its default speeds - go into the BIOS and set the RAM back to 133MHz.

Common Memory overclocking errors are: Programs closing themselves, memory and vitual memory addressing errors, anomolies while loading text files, BSODs, windows freezing, data loss, and inability to enter windows without a reinstall.

 

[FatPat]

I've been reading the posts here looking for info I can use to setup my memory settings. I'm real dumb about understanding how to determine what memory settings to use. I have an MSI 875P Neo-FIS2R mobo and a P4/3.0CGHz 800M 478P CPU, WD Raptor 36.7GB SATA 10K drives, and
2 sticks Corsair CMX512-3200C2PT 512MB.

In the past I just used 2,2,2,2,5 with my Northbridge 1,6a @ 2.12 GHz. I don't really need to o/c the memory much. I just need to know what the normal/default settings are.

I didn't get into CPU o/c yet, but I bumped to 3.06GHz just to start. I thought I'd wait to see if I could see what others are doing. Especially since I'm having trouble just getting the Sata drives setup so I can install Xp. I have to flash the bios with 1.5 yet. Thanks in advance for any info/help.

P.S. I don't want to have to use a special fan/heatsink.