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Is memory Quantity better than CAS timing / speed?

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January 2, 2006 10:50:18 PM

I have an interesting question. I have an older P4PE ASUS motherboard that I use with a 3.06GHz 533MHz FSB CPU. I have two memory types at my disposal; 1Gig (2 x 512MB) Corsair XMS3200OC2 and 2Gig ( 2 x 1Gig) Corsair VS2GBKIT400C3 value RAM. Both are running at PC2700 with no overclocking. I selected this memory set because my board does support 800MHz FSB with the newer CPU's, and I wanted to reserve the ability to use one later on if I saw a decent deal.

The big question is, is more memory (2GB) better than faster, but less (1GB), memory? The game industry seems to think that 2GB is what you want, and some sites say less, but faster, memory is better.

Since I don't currently run the PC3200 memory faster than PC2700 speeds, I suspect that I can get the timings down on my VS2GBKIT400C3 value memory to CAS2 or so, true? Or does the memory bus speed decrease from 200MHz not improve the memory timing ability?

Also, Intel chipsets seem to be less sensitive to all out memory speeds than AMD systems (not quad pumped). Is my Intel 845 chipset not going to really care unless I overclock well above PC2700 speeds?

What would you use, either 2GB of VS2GBKIT400C3 or 1GB of XMS3200OC2, and why? Obviously, if I can get the VS2GBKIT400C3 to run at the same timings as the XMS3200OC2, use the 2GB, but if I can't, when would you decide to use less, but faster memory? What memory would win this shoot-out, and under what circumstances, with my 533MHz FSB CPU?

I'll do some playing around with the memory, and timings, and see what I find (3Dmark) but I don't have the definitive answer to this test with just 3D mark numbers.
January 3, 2006 1:11:29 AM

This is a very good question with which does not have so easy an answer. I think we can come close though.

What it really comes down to is your applications' needs.

If an application, regardless the type, does not use close to the 1GB of ram you have in your system then the faster memory timings will indeed show an improvement over the slower 2GB of memory.

However, if an application does require more memory than your 1GB will allow then the thrashing (hard drive page file access) will cripple your system in comparison. The slower hard drive access will show a marked degredation in performance well beyond the benefits you will recieve from the faster timings.

Ideally, the best solution would be to get 2GB of fast memory. But we all know that isn't always possible.

So, in your situation I would suggest going with the 2GB if you find that any application you use demands it.

Hope this helped.
January 3, 2006 1:48:06 PM

I'll let you know what 2Dmark says. I hope that the PC3200 2GB RAM can be set more aggresive with my PC2700 (166MHz) memory bus speed with my 533FSB CPU. Most memory can be run tighter if you slow it down.

I pretty much found out that my CPU can't be overclocked enough to use the 200MHz (PC3200) memory timings at all, so why bother. But, I can take advantage of that fact and use CAS3 PC3200 memory at PC2700 speeds and try to run it at CAS2.

I do believe that value RAM at CAS2 and 2GB would be better than the 1GB XMS memory at CAS1 or 1.5 timings.

Still, I don't think that memory is a very good place to improve performance costwise (if you have 1GB or so) compared to a better CPU (my 3.06GHz 533FSB CPU is already about as fast as you get in my PC's generation) or video card (my ATI X800XL is about as good as you get in an AGP 4X slot).

My XMS memory stick died and I got the value RAM to max out my board at a reasonable price, and hopefully adequate timings. This PC will just have to live out it's life as is from now on.
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January 5, 2006 12:04:50 AM

Why not run ur memory at 133MHz (PC2100) instead of 166MHz PC2700? since ur processor is a 533FSB, which is actually 133x4, then if you run ur value select 2GB at 133MHz, I'm pretty sure your ram will be able to do CAS2 at PC2100 speed
January 5, 2006 7:04:55 PM

I believe that DDR333 is running double pumped at 333MHz/2 = 166MHz where DDR400 is at 200MHz, correct? And, PC2700 3= 33Mhz ECC memory.

The 533FSB CPU speed ties in with the DDR333 memory requirement. Since the FSB can handle more memory bandwidth than the DDR333 pumps out, some try to go up to 400MHz effective clock on the memory. This is why I bought PC3200 RAM.

You have a good point, though. Is a slower memory clock with tighter timings better than as fast a effective clock and looser timings?
January 8, 2006 2:27:50 AM

No, for an Intel Pentium 4 system, having a higher memory bandwidth (higher clock speed) is more important than having a slower memory speed with tight timing.

I said that because I thought that your motherboard supports Dual Channel memory interface, if so, running 2GB of memory, at PC2100 speed with Dual Channel enabled, it should be optimal for your system, you can think of PC2100 Dual Channel as "PC4200", which will result a system memory bandwidth of 4.3GB/sec, and it perfecly fits with a Pentium4 @533FSB.
BUT, I did a bit of research of your motherboad, your motherboard is based on Intel i845, which supports only Single Channel memory..

therefore, I believe that having a faster clock speed w/looser timing is more important than having a slower clock speed w/tight timing.

Correct me if i'm wrong :wink:
January 8, 2006 3:27:03 AM

While on the subject, anyone have any particular recommendations for AMD systems?
Athlon2500@2.2
Abit NF7 v.2
Zalman HS/120mm fan
Currently 2x256 PC3200 value RAM, 2.5 3 3 8

I'd like to keep the dual channel feature and was going for 1 Gig TCCD but now I'm thinking of going to 2 GIG's but haven't seen any that impress me. I do applications w/heavy CPU loads also but still run in the hi 40's.
January 8, 2006 6:47:37 PM

I ran XMS PC3200 @ 2.5-2-2-6 with 1Gig total, and Value RAM PC3200 @ 2.5-3-3-7 with 2GB total. The speed difference was less than 2% in 3DMark05. I didn't just test just the memory because I don't use just the memory. I use the whole PC.

Game load time are about half (Doom 3) as long with the cheaper timing RAM, and that WAY offsets a 2% drop in test score. It can't be too much more significant in game FPS's.

I'll pocket the extra hundred bucks for value RAM on this PC anytime and anyday. On the performance per buck angle, the looser timing and bigger amount wins hands down in my book. If cost were no object, we wouldn't need this discussion. May as well go for as low a timing as exists and as much as your PC will hold. Cost is an issue, and I think most people spend way too much on memory for what they get out of it. I was included in that group. Next time? My money goes for a fastest video card, then CPU. And the memory? Amount is first with timing a distant last.
January 8, 2006 7:39:22 PM

Thanks, I think that tipped it for me, since some of my TIFF files are 80Mgs
and larger the 512M I have now leaves me in the swap file a lot. My timings
are already slightly looser to maintain really good stability, I expect I will have to run CS 3 tho. As moderately as this rig is overclocked it's more sensitive to things like RAM timing.
!