What's better to overclock - RAM or CPU? (Can't have both it seems)

[Fun Guy]

My RAM doesn't go up to 150, but it goes up to 140 (Crucial CAS2). So these seem to be my max choices between RAM and bus speed on my motherboard/CPU combo (AOpen MX3S-T/Tualatin 512K 1266Mhz) while still keeping everything stable:

- RAM @ 140, System Bus @ 140, PCI @ 35, CPU at 1330
- RAM @ 120, System Bus @ 160, PCI @ 40, CPU at 1520

Which one will be faster? What utilities can I use to test it?

 

[BD231]

140/140 all the way dude. You'll increase mem latency if you run your mem any faster than your FSB. That could give you stair step effects in games. Running your mem at 120 would gimp the P3 at such a high clock also.

 

[oldfart]

That Crucial cas2 ram should be able to go to ~ 160, but with cas3 timing. I also run a PIII-S 1.26. I hadCrucial cas2. It would do ~ 145 2-2-2. I now have some OCZ stuff that will do a little better. Running your mem 133/100 will give you a HUGE performance hit. My system is setup 158 FSB, 1.5 GHz, 1.5 Vcore ,2-3-3 timing. Set you mem to more conservative timings and you should be able to go higher. The PIII-S can easily handle it. Use Prime95 to test stability.

 

[SaiyaJim]

You just need to find a happy medium. What I suggest is doing what I did. Sit down with a pad an paper, set your multi do default, and step you fsb as high as you can, until you cant even POST. Lower it one notch, boot windows and do a Sandra Test, and a 3dmark test. Run 3dmake 3-5 times and take the avg of it as it will bounce around a bit. After you finish that, lower your multi a half step and repeat process until you find your best scores.

Wait, nm... PIII... sorry, not much help there....

 

[LarryJoe]

You are better off turning your CPU down and running the memory at the faster speed. In my case, I can run my P4 at 2.7, but the memory won't do 533, so I have to run it at 400. So, I prefer to run the P4 at 2.6 with the memory at 520. All Sandra tests support the latter being faster.

 

[Plester]

i have the same board and the problem is it does not have a wide variety of fsb speeds above 140 and many of them run the ram async - no independent control over ram.

just for sh!ts and giggles i tested Q3A for you at 140/140 and 144/108
144/108 - Q3A at fastest = 160fps
140/140 - " - 193fps

kind of obvious that unless you are crunching numbers or something purely dependent on cpu speed, you want the mem bandwidth.

 

[Fun Guy]

Wow, thanks for the great replies.

Okay, I think I understand that I need to keep both the RAM and FSB at the same speed, and that memory throughput is more important that raw CPU power. Now for the big question ...

I can get 150/150 (FSB/RAM) but only for a little while before Prime95 takes a dive (actually, sirens go off too, but that's another story). This is with my memory at highest settings in BIOS:

- SDRAM CAS Latency Time ......... 2 or 3 ......... (I have 2 selected)
- SDRAM Cycle Time TrasTrc ........ 5/7 or 7/9 .. (I have 5/7 selected)
- SDRAM RAS-to-CAS Delay ......... 2 or 3 ........ (I have 2 selected)
- SDRAM RAS Precharge Time ..... 2 or 3 ......... (I have 2 selected)

Which settings should I fiddle with to get this thing stable at 150/150/1425?

 

[oldfart]

First off, you can go past 150 FSB easily. Are you trying to get the most out of it or are you conservative? I have spent a lot of time with my PIII-S and have tried almost evry combo. If you want 150 FSB, start with the slowest settings, then work backwards. Try this:

3,3,3 7/9
3,2,2 7/9
2,3,3 7/9
2,2,3 7/9


Start at the top and work your way down. Run P95 for each setting. To run 2,2,2 5/7 you will only be able to go to 145 FSB or so. I think for 150 FSB, you will wind around a 2,3,3 7/9 or 3,2,2 7/9.

I run 158 FSB, 2,3,3 7/9, but my ram is a little better.

 

[Fun Guy]

oldfart, you da' man. Thanks for your replies.

I have Mighty-Mite up and running 150/150/1425 in Prime95 right now at 3,3,7/9,3 (actually, I am a little confused as to how you ordered the recommended settings in your post since the way you put them does not coincide with how I wrote them down...how do your recommended settings map to the setting names?).

I would love to max this puppy out, but of course after a while I realize it's like splitting hairs. I guess I would be happy with this little box going as fast as it possibly could while still being stable. I wouldn't mind 158/158/1500, but would settle for 150/150/1425 if that's what the max turns out to be.

By the way, I would appreciate anyone who can recommend tests for stability in addition to Prime95.

Probably the best thing to come out of this exercise is the realization that Crucial is not the best RAM for overclocking. It is fine for my video editing box (no overclocking required there) but next time I will probably go for the Mushkin High Performance or some other alternative for my hot rod machine.

Thanks again to those who replied - you guys are great.

 

[oldfart]

Overclocking with a high FSB is tricky. Where do you start? How do you know if the CPU or ram is pushed too far? I kind of set a limit of FSB and Vcore. I wanted ~ 1.5 Ghz, which worked out to 158 FSB. I didn't want to go over 40 MHz PCI, or have to up the Vcore too much. I played around and found 158 MHz FSB to be a good balance for my system. First, set all mem timings as slow as possible (3,3,3 7/9). At 1.45 Vcore, I'd get Prime95 errors. Prime95 stable @ 1.5 Vcore. That is not too bad a bump. Now that I had a stable CPU, start with the ram timings.

When I say 2,3,3 7/9 it means CAS Latency Time, RAS-to-CAS Delay, RAS Precharge Time, Cycle Time Tras/Trc. If you are at all up in the FSB ranges, you always have to go to 7/9 on the Tras/Trc. So the rest is easy. The CAS Latency Time is the most important. Try to keep that 2 if possible. 2,3,3 is faster than 3,2,2. If you have to go 3,3,3 7/9 to get to a higher speed, dont sweat it. It will still be fast.

 

[Fun Guy]

Okay, 150/150/1425 was no problem at 3-3-3 ..... 2-3-3 bit it fairly quickly, after an hour or so. Been running Torture Test for 15+ hours at 3-2-2 nary a glitch.

So, Question One is - do I go out and spend money to get from 3-2-2- to 2-2-2? What's the big diff anyway? Would I ever be able to tell?

And Question Two is - after 24+ hours of Prime95 can Mighty-Mite be 'Certified' stable? Do I need to run anything else to be assured?

 

[oldfart]

The small speed difference is not worth getting new ram. If you are looking for more speed, you can go past 150 FSB and see how it goes. If you can run Prime95 24 Hrs, you should be OK. Serious Sam is another good test. It will crash if everything is not just right.