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wnd
09-05-05, 12:33 PM
This must be the millionth time asked, but quick search for the answer didn't reveal much. In case these questions have already been answered, I apologise in advance. Anyway, it would be interesting to hear different and fresh opinnions on this.

I'm building a new set-up to replace my good old XP2700+ / 9800Pro with the following:
- Asus A8N-E (nForce4, Socket 939, Dual Channel mem)
- AMD Athlon 64 3500+ (Venice, Socket 939)
- nVidia 7800GT (Gainward)

The primary question at the moment is the memory. I have already ordered a pair of PC3200 (400 MHz), CAS 3 memory (Kingston Valueram 1GB Kit) for 112 (or USD 140) -- an order which I can cancel at any time. The price is probably a rip-off, but pretty much the best deal I could find _available_ at the moment in Finland. At first I was looking at separate pair of CAS 2.5 timed 512 MB chips for 48 each, but started to doubt if this would work dual channel.

So to my question: how much will I gain by getting better-timed memory such as already mentioned CAS 2.5 or 2.0? How likely is it that two separate memory chips, purchased at the same time from a big retailer, will work dual channel? Will I actually see the difference between single and dual channel, or different memory timings in normal gaming (say, Battlefield 2, Unreal Tournament 2004)?

And just as a disclaimer: I'm not looking for killer gaming system, just wonder what sort of hardware would give the most for the money. So, comments, advices, experiences. Any feedback is welcome.

uOpt
09-05-05, 12:53 PM
You will pretty much certainly be able to run dual-channel with the two modules you bought. I never bought a kit and all my modules work in dual-channel mode.

In applications that are not graphics card limited and that use decent amounts of memory at the same time you will see about a 3% advantage with CAS 2 over CAS 3.

Your Kingston Value might also very well turn out to work fine with tighter timings.

In general, RAM for AMD64 CPUs is not worth worrying too much.

Even if you overclock this holds true, because you don't have to overclock the RAM if you don't want to or cannot.

Your only worry here is that BF2 is not really happy with 1 GB RAM. If you are a heavy BF2 player it is much better to get cheap RAM and try to upgrade to 2 GB sooner.

toxikneedle
09-05-05, 01:36 PM
Your only worry here is that BF2 is not really happy with 1 GB RAM. If you are a heavy BF2 player it is much better to get cheap RAM and try to upgrade to 2 GB sooner.
Well a lot of people have said that 7800s perform much better with 2 gigs of ram in the system.

wnd
09-05-05, 01:44 PM
You will pretty much certainly be able to run dual-channel with the two modules you bought.

That I wasn't so worried about. :-) I was just wondering if I could save some 20 and go for two single-sold 256 MB chips instead of more expensive kit.

In applications that are not graphics card limited and that use decent amounts of memory at the same time you will see about a 3% advantage with CAS 2 over CAS 3.

That's what I read from tomshardware.com, but with all the "information", conflicting with each other, I couldn't make up my mind. Thanks for furher assuring me I don't need to go the more expensive way.

Your Kingston Value might also very well turn out to work fine with tighter timings.

Are there any danger in damaging the chips, or will I just getting memory corruption if timings are set too high? I used to have some bulk 256 MB/266 MHz chips with one of my old motherboards. When I updated to my current CPU, I started running the memory 333 MHz without really remembering the memory was 266 MHz. Not too long after that I started having random crashes, which proved to be an indication on faulty RAM. I'm planning not to let that happen again.

In general, RAM for AMD64 CPUs is not worth worrying too much.

What exactly do you mean? I read integrated memory controller of AMD64 is rather good one, but I don't know any details. Can you shed some light?

Even if you overclock this holds true, because you don't have to overclock the RAM if you don't want to or cannot.

While it's more likely that I will underclock some stuff to make the system more quiet (like that would make any use with 7800GT), this is good to know.

Your only worry here is that BF2 is not really happy with 1 GB RAM. If you are a heavy BF2 player it is much better to get cheap RAM and try to upgrade to 2 GB sooner.

Thanks for advice. I've tried my best to keep my options open by having Socket 939 (maybe having AMD64 x2 when Unreal 3 come out) and only half of memory sockets populated. I was planning to give 1 GB a go, and get another 1 GB if it's not enough. Hopefully memory prices will also drop before then. :-)

Thanks for your (quick) reply, I appreciate it.

wnd
09-05-05, 01:45 PM
Well a lot of people have said that 7800s perform much better with 2 gigs of ram in the system.

Considering that 1 GB is "only" four times the GPU memory on stock 7800GT I'm not exactly surprised. Thanks for friendly reminder nevertheless.

wnd
09-05-05, 04:13 PM
Yet another question: if I have a matching pair of 512 MB DIMMs, dual channel set-up working, and add a single 512 MB DIMM, what will happen to dual channel memory architecture (in case of set-up I described before: motherboard with nForce4, AMD64 Venice)?

Superfly
09-06-05, 04:36 AM
you will loose dual channel.

Toss3
09-06-05, 04:40 AM
Niiiice another forum member from Finland! :) Now I'm not the only one!

saturnotaku
09-06-05, 06:06 AM
Thanks for advice. I've tried my best to keep my options open by having Socket 939 (maybe having AMD64 x2 when Unreal 3 come out) and only half of memory sockets populated. I was planning to give 1 GB a go, and get another 1 GB if it's not enough. Hopefully memory prices will also drop before then. :-)

If you do that, your system FSB/HT will drop to 166 instead of 200, and you'll be force to run the memory with a 2T (instead of 1T) command rate, which will cut your performance by at least 10-15%. It's better to plug in two, 1 GB sticks instead of 4x512 on the A64.

wnd
09-06-05, 05:59 PM
If you do that [4 * 512 MB], your system FSB/HT will drop to 166 instead of 200, and you'll be force to run the memory with a 2T (instead of 1T) command rate

Sounds like incredibly bad hardware design to me. Does this apply to my specific motherboard, chipset, AMD64, or just dual channel? While I have absolutely no knowledge on this, I'm rather skeptic. I suppose you have some sort of reference for this, I would be more than interested to read more.

wnd
09-06-05, 06:02 PM
Niiiice another forum member from Finland! :) Now I'm not the only one!

Which further means nearly 10% of Finns use this forum. Well, almost. :-)

saturnotaku
09-06-05, 09:24 PM
Sounds like incredibly bad hardware design to me. Does this apply to my specific motherboard, chipset, AMD64, or just dual channel? While I have absolutely no knowledge on this, I'm rather skeptic. I suppose you have some sort of reference for this, I would be more than interested to read more.

It's mainly to do with the on-die memory controller of the Athlon 64. Back when Socket 939 first came out, it was nearly impossible to run with all DIMM banks filled on any motherboard. Now, with the Venice cores, it is possible to at least run with 4 banks at the lower HT speed and 2T command rate.

This has been discussed on this forum before, and (google) is your friend as well.

Viventis
09-09-05, 02:40 PM
It's mainly to do with the on-die memory controller of the Athlon 64. Back when Socket 939 first came out, it was nearly impossible to run with all DIMM banks filled on any motherboard. Now, with the Venice cores, it is possible to at least run with 4 banks at the lower HT speed and 2T command rate.

This has been discussed on this forum before, and (google) is your friend as well.

I'm not sure abou the Venice core, but the San Diego can run 4 banks of double sided memory at 2T without lowering the FSB/HT speed from 200 to 166. See the article here:

http://www.bleedinedge.com/reviews/processor_reviews/3700sd/3700_San-Diego_02.html

My system is living proof that the article is accurate. I have an AMD 64 3700+ San Diego running 4x512 of Corsair memory at 200, 2T. (Geforce 6800 GT AGP; Asus A8V Deluxe) Since going from 2x512 to 4x512, my 3DMark 2004 score went down 5%, my 3dMark 2005 score increased a couple of points, and I have noticed no measurable fps loss in games with fraps. I have all settings in Battlefield 2 on High with no stuttering, even at the very beginning of the maps.

wnd
09-10-05, 07:12 AM
Thanks for informative replies everybody. In case you're interested (which I doubt), I ended up getting a brand new 2 GB kit of PC3200, CAS 2.5 thru eBay. Twice the amount I planned, faster than I planned, and not so expensive either (USD 225 as opposed to over USD 325 from Finland). My new system is up and running, having my old memory, 768 MB of PC2700, CAS 2.5 installed. Now all I have to do is to wait for my memory upgrade to arrive.

Again, thanks everybody.