Do I understand this correctly?

First, not quite the main question, why would you want to run your memory faster than your CPU bus?
I read that 3:4 and 4:5 memory ratios are more desirable than 1:1. I am planning to get the Intel 2.8 @ 175 FSB. At this speed, the memory speed would be 437.5 @ 4:5 and 466 @ 3:4. Do I need to get DDR466 to pull this off? I hear Corsair DDR is great at OCing and I would like to get one or two sticks of this: http://www.googlegear.com/jsp/ProductDetail.jsp?ProductCode=85013-1 in an ABIT IT7-MAX2. Would DDR433 or 400 be ok for both these speeds? If I got the DDR433 instead of the DDR400, and I did a slight OC in the 433 instead of a more significant OC with the 400, would it run more stable? Thanks for any help

Also... =)
Would it be better to run the memory at 2-2-2-5-1 at a lower MHz or default at higher MHz?

Ok well i willt ell you what i know about what you are asking...First personally i dont know why people run there memory faster than there FSB...i mean whats the point of that, you can only transfer as fast as the weakest link, so if everything is running the same speed there are no bottlenecks, so a 1:1 or sync would be most desirable, if u ask me...I am however used to AMD platforms, not intel...

As for the timings and lower mhz question, I run as fast of FSB as i can, mostly because that gives more of a preformance boost in overall system preformance for me...but your system, and anyone leses system could be different, crank your FSB up as high as it goes, tighen your timings, and run a memory bandwidth benchmark, then try the other way, see what preforms better for you, its different for everyone, and the subjust is pretty divided on this forum of which is better, so you need to fuind out for yourself

I hope that helps

Matt

For AMD systems running memory faster is useless.

For intel the reason is that intels (P4) FSB is quad (x4) pumped. So lets say you have DDR memory which runs at 2 times the FSB. Now you have a FSB of 10. The Intel CPU is running at 10 X 4 which is 40 but the memory is only running at 10 X 2 = 20. So basically the memory is only using half of bandwidth that the CPU can actually handle. So by running the memory at a 3:4 ratio you can have the CPU still at 40 but the memory is now running closer to the bandwidth that the P4 can handle. Thats a very quick explanation, but I think it can clear it up.

Ah so the intel platform is differnt, well yeah, im remeber that next time...

Thanks for correctin me

cack01 said:

For AMD systems running memory faster is useless.

Click to expand...

i'm not sure if i agree with you. but you can tell me if i'm wrong. i have an amd 2400xp+ right now running at 2150mhz (15x, 143/36). i have a stick of 512mb samsung 2700 running at, i believe, 356mhz. if i run it in sync with the cpu, meaning around 286, my scores in 3dmark2001 are about 12700. but if i set the memory to 356, my scores jump up to 13200. that's leaving all other settings the same. i can understand the logic with the bottleneck being my cpu...but why would my scores be higher. or should i disregard the results of 3dmark2001? motherboard is asus a7v8x.

What we are talking about is running the memory at like 120% of the FSB, running the memory at a faster frequency than the FSB, THAT is usless on a AMD system...but running sync, and upping the FSB DOES increase preformance, so yes you are right, you just misunderstood what we were saying...

Thanks guys, so if ur FSB was 10, DDR = 20, QP = 40... 3:4 ratio means your memory will run at 13.3?

Would you recommend getting faster memory and doing a small OC or get slower mem for a lil cheaper and push its limits (im looking at corsair 3200 vs 3500)?

Well it depends on the chip you want to get. Earlier you said you wanted 2.8 @ 175 FSB so that means your getting a 1.6 (If my assumtion is right of course). The 3200 is more then enough and your probably going to be able to run some fast timings on the RAM too.

P.S. Personally I'm not sure the 1.6 can get upto 2.8. I bet a 1.8 can though.

hehe, 2.8 @ 133
3.6 @ 175 ; )
Ok, this seems to make logical sense buuut... since the memory's stock clock speed is higher (DDR433), the small OC that I would have to push would result in my ability to get higher timings? Thanks so much for the information guys =D

The 3200 should be fine. Its rated at 200 so at 175 you should have enough headroom to have some pretty fast timings.

In summary:

AMD: Keep the memory in sync with the bus.
Intel: Just crank it up and watch the numbers fly

Also, if you're really planning to take a 2.8GHz P4 up to 175fsb....sorry, bro. No can do. I've never seen a 2.8 get that high, they're notorious for not liking to overclock to high fsb speeds because they have a 21x multiplier. I used to have a 2.8, I traded it for this 2.4B I have now because I can now do about 160-166fsb. My old 2.8, and most owner's of 2.8's usually hit the wall at 150fsb (3.15GHz).

Now this isn't set in stone, but it's a general trend from what I've seen, plus my experience. Of course, I have seen 2.8's go higher, but that was with Prometeia or Vapochill cooling, as well as voltmods going wayyyyyyy up. Sometimes even over 2 volts!!! BTW - over 1.7 volts is where you start taking risks with Northwood P4's.

And also, for anyone looking for high fsb's in P4 systems, I highly recommend a dual channel DDR memory motherboard. At 166fsb, I get over 4GB/sec of memory bandwidth in Sandra.....and that's with very slow timings