Need to upgrade to C2D but don't quite understand FSB+RAM details

[Fraggable]

I've always been an AMD guy since they were traditionally cheaper but now I need to upgrade and C2D is the obvious only choice. I've noticed that the C2D FSB is 1066MHz. Now, with my A64 3000+ Venice I went with PC3200, 200/400MHz memory since it matched the FSB speed. Do I need 1066MHz DDR2 to take advantage of the C2D or can I use slower RAM without killing performance too much?

I saw a few skt. 775 boards on newegg that support C2D and older PC3200 DDR. I'd really like to hang onto my $200 worth of memory for a few more months, am I insane for using memory that slow with that kind of CPU?

I'm planning to get the E6300. I don't plan to OC, at least until I get DDR2 memory and a better mobo in 8 months or so.

 

[Accord99]

Originally posted by: Fraggable
I've always been an AMD guy since they were traditionally cheaper but now I need to upgrade and C2D is the obvious only choice. I've noticed that the C2D FSB is 1066MHz. Now, with my A64 3000+ Venice I went with PC3200, 200/400MHz memory since it matched the FSB speed. Do I need 1066MHz DDR2 to take advantage of the C2D or can I use slower RAM without killing performance too much?

http://www.xbitlabs.com/articles/memory/display/core2duo-memory-guide_6.html

 

[n7]

Originally posted by: Accord99

Originally posted by: Fraggable
I've always been an AMD guy since they were traditionally cheaper but now I need to upgrade and C2D is the obvious only choice. I've noticed that the C2D FSB is 1066MHz. Now, with my A64 3000+ Venice I went with PC3200, 200/400MHz memory since it matched the FSB speed. Do I need 1066MHz DDR2 to take advantage of the C2D or can I use slower RAM without killing performance too much?

http://www.xbitlabs.com/articles/memory/display/core2duo-memory-guide_6.html

Great guide btw.

To clarify your question OP:

Intel uses a quad pumped FSB, meaning the actually FSB runs @ 266 x 4 (1066)
Therefore, to run RAM @ the same speed as the FSB, you merely need DDR2-533/PC-4200 (266) RAM.
Running faster RAM means it's running at a higher than 1:1 ratio.

I'll use my system as an example.

I run CPU @ 8x425 (3400 MHz w/ 1700 MHz FSB)
I run the 4:5 divider for my RAM, which puts it @ 531.25 (DDR2-1062.5)

You could indeed use your existing DDR with one of those AsRock mobos that supports both.
Look on the main AT page to see the reviews they did of that.

 

[Golgatha]

Quote from the x-bit article above.

"In other words, you can achieve maximum performance by using memory with lowest possible timings in synchronous mode. It means that if you overclock the FSB to 400MHz, DDR2-800 SDRAM with low timings is the optimal choice. If the FSB is overclocked more, DDR2-1000 or DDR2-1067 SDRAM is the best option. An additional argument in favor of using memory and the FSB in synchronous mode at overclocking is that the 1:1 divisor is the most stable one on a majority of mainboards."


I run my E6600 at 333Mhz (1333 Quad FSB) with 1:1 divisor and 4,4,4,12 timings. I personally think you should just bit the bullet and switch to DDR2 memory. Even AMD is going to DDR2, so I'd say it's a safe investment.

 

[Fraggable]

Thanks for the explanations, that really helps.

I'm sure DDR2 is the future and all that but I don't have $200-300 to spend on another 2 gigs of ram in order to play BF2 like I do now. If I can get a ~$50 board to use for a while I think I'll do it as long as it's not making the CPU investment worthless.

 

[Ryan Norton]

So... sorry to dredge this back up, but I'm also coming over from the AMD world.

I have an E6400 sitting on the shelf and I'm going to bite on a motherboard as soon as AT's P965 roundup comes out and I get a chance to digest. That leaves RAM.

So at default settings, my mobo will be running a 4x266 FSB. For RAM to run at 1:1 with the default, stock, non-OC'd FSB, all I need is DDR2-533 a.k.a. PC-4200 RAM, I'm assuming ideally at the lowest possible latency.

But let's say I want to do an easy, non-finicky, and definitely achievable overclock with the E6400, to 3.2GHz (E6400s all hit that on air, right?). I'm still assuming that 1:1 is the best RAM divider, and since I can't raise the 8x multi on the E6400, I will have to run the FSB at 400MHz. That means my RAM has to be rated to run at 400MHz, DDR2-800, PC6400.

Are all of my assumptions solid? Because if they are, then I'm going to be 2x1GB DDR2-800 at the lowest latency I can find.

My last question is, I have heard of issues with boards being unable to post with DDR2-800 RAM installed, due to RAM manufacturers cheating a bit and not rating their sticks stable at DDR2-800 on less than 2.1v. Does this still seem to be the case? Should I find a $10 stick of DDR2-400 or -533 so I can post and change the timings from their SPD defaults on my DDR2-800 sticks?

So to recap my plan, for your approval:

1. E6400
2. P965 mobo (P5B Deluxe unless the AT roundup says different)
3. 2x1GB DDR2-800 RAM.
4. Upon assembling, things will run at stock speeds with no trouble UNLESS I run into the voltage default conflict.
5. I can get an overclock to 400MHz FSB, 3.2GHz CPU, and DDR2-800 on a 1:1 RAM divider. Any higher FSB/CPU and I've got to use fractions.

Thanks for all the info I always get here!

 

[Fraggable]

I have 6 new desktops at work that I recently built, they're AM2 systems. I had to use one of the 3 sticks of DDR2-800 that was 'certified' to work with the boards. BIOS updates give better compatibility but yes, you will need a stick of slower memory to do the update.

Do your research and see what's working with the board you choose and you'll probably be fine.

 

[n7]

Originally posted by: Ryan Norton
...snip

1. E6400
2. P965 mobo (P5B Deluxe unless the AT roundup says different)
3. 2x1GB DDR2-800 RAM.
4. Upon assembling, things will run at stock speeds with no trouble UNLESS I run into the voltage default conflict.
5. I can get an overclock to 400MHz FSB, 3.2GHz CPU, and DDR2-800 on a 1:1 RAM divider. Any higher FSB/CPU and I've got to use fractions.

You've got it :thumbsup:

However, just FYI, there are no lower than 1:1 ratios for you to use (unlike with AMD), so if your RAM craps out at 820, you ain't gettin' past 410 FSB

To save you hunting around, here's the RAM you want :
Team Group DDR2-800 4-4-4 (2.0-2.2V)
http://www.tankguys.biz/ddr2-44410-800m...sCsid=79ed553564e06bb5393fe80cdb0976b9
This stuff will pretty much always hit DDR2-1000 speeds if you loosen timings a little.

 

[stevty2889]

Originally posted by: n7

Originally posted by: Ryan Norton

However, just FYI, there are no lower than 1:1 ratios for you to use (unlike with AMD), so if your RAM craps out at 820, you ain't gettin' past 410 FSB

Not entirely true, at least with my P5W DH, there is a DDR-2 400(PC3200) option, so there is one option thats less than 1:1.

 

[Ryan Norton]

Thanks guys, you rock. Now the only problem is that I'm living in Taiwan, "NewEgg" means over here a big collection of little vendor stalls and tiny shops in an IT park, and each one has at most 4 brands of DDR2, weird ones who don't seem like they're in the US market yet: Kingbox, Apacer, etc. Haven't looked into prices to closely but I imagine Corsair, OCZ will be pricier than I expect. So maybe I'll end up with looser timings than I ideally want

Thanks again!