Athlon memory controller

[prosserd]

hi,

I'm talking to a computer sales guy (who sounds quite knowledgable to me) and he has said the following to me:

===
RAM performance of current AMD Athlon platforms, regardless of model will always take a hit after 2 x 1gb, Athlon has the memory controller on the CPU - which does have its advantages - but currently in some ways is more of a hinderance. Intel platforms have the controller located on the board, which means it can be larger, more flexible (and better cooled) so if memory bandwidth is an issue, then Intel is a better choice.
===

It sounds reasonable enough and have no reason to doubt it - but after searching a lot through Google and various hardware sites I can't find any information to confirm this.

Can anyone point me to an article or two about this problem? (I am also interested in whether this is a matter of opinion or a documented fact - which is why I am asking you guys instead of the salesman).

I am wondering (if it is confirmed fact), how much %-wise that it slows down the RAM.

Dan.

 

[shortylickens]

Which Athlon?

The Athlon A, (which was a slot A CPU)?
Probably.

A socket 939 Athlon 64?
I highly doubt it.

EDIT: I just reread his statement. The guy know two things: Jack and sh1t. And jack left town.
Both companies have made their modern CPU's with the memory controller on the chip, which (near as I can tell) is ALWAYS better. Whether using fast or slow RAM, a lot or a little.
It just took a while to refine the technology, but thats what the CPU designers have been wanting to do for a long time. There are way to many limitations on using the Northbridge to control memory.

 

[orangat]

The memory controller is indeed on the AMD 64 cpu. The problem is that memory runs at PC2700 instead of P3200 and 2T when you fill up all 4 slots on 939 systems. The good news is that the performance hit is mostly negligible in real world apps.
Zebo has 2 threads on ram performance if you are interested in benchmarks so search.

And venice cores improved on this problem so they only suffer from 2T which is a very small impact.

 

[evilharp]

Comparing the memory performance of the A64 to the P4 is like comparing apples to oranges.

The P4 uses DDR2 (now) the A64 uses DDR.
The P4 memory controller is limited to the FSB speed the A64 controller scales with CPU speed (higher = faster)

As for the sales guys quote, well, he's full of it (does he work for Dell?) The A64 contoller only takes a "hit" if you populate all 4 Dimm slots (this is being debated) and if you run 4 gb of Ram in a 32 bit environment.... but wait 4gb of ram is a 32-bit OS limitation (addressing limit) whereas A64 can run 4gb+ in a 64-bit environment.

Bandwidth isn't a big deal for the A64, the controller is extremely efficient. Look at this thread for more details: http://forums.anandtech.com/messageview...atid=28&threadid=1475190&enterthread=y Besides, if you want more bandwidth buy faster ram (>DDR400), but it wont make much of a difference (http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2497)

Finally, the sales guy refers to "better cooling" with Intel. That is a laugh. Intel has a huge problem with heat right now, leading to frequent "hotplate" and "toaster oven" jokes amongst forum members.

 

[prosserd]

hi,

Thanks very much for the (very) fast responses - much appreciated.

I did some reading of the threads suggested and (not knowing what 2T was) I can see that the impact of being 2T appears to be minimal from Zebo's "real world" testing.

Also I am planning to run 4 slots 4 x 1 GB OCZ

The guy is recommending OCZ Platinum but I also read in the other thread that the Value stuff is nearly as fast.

thanks,

Dan.

 

[w00t]

get two 2gig sticks instead the memory controller ont he amd64 isnt ment to support more plus it will raise your temps higher.

 

[Some1ne]

EDIT: I just reread his statement. The guy know two things: Jack and sh1t. And jack left town.
Both companies have made their modern CPU's with the memory controller on the chip, which (near as I can tell) is ALWAYS better. Whether using fast or slow RAM, a lot or a little.

Where do you get your info? No currently available desktop CPU from Intel has an integrated memory controller. The memory controller is still part of the chipset when working with Intel products.

The tech is correct in that if you try to have 4 GB of RAM by doing a 4x1GB configuration, you will see a performance hit. If on the other hand you do 2x2GB, there will be no performance hit from running 4 GB of RAM on the Athlon64. On an Intel board with 4 RAM slots, you could do 4x1GB with no performance hit.

He is partially correct about bandwidth. The P4 in theory has more of it. In practice however, the P4's memory bandwidth is limited by the FSB, and the AMD64 actually ends up getting just as much if not more bandwidth than the P4. Also, the AMD64's integrated memory controller affords much lower memory latencies than the P4's chipset-base solution, which is always a good thing, and it also lets you run a divider without seeing the sort of penalties that you get on Intel solutions when running a memory divider.

 

[l Xes l]

dont listen his ass. just get A64 CPU w/ 2 x 1gb Ram sticks..

 

[Fern]

Hi prosserd and Welcome to the Forums!

4gigs huh? I don't use winXP but am wondering if it can actually make use of 4gigs? Be a shame to blow the $ and see no improvement.

Fern

 

[evilharp]

Originally posted by: prosserd
hi,

Thanks very much for the (very) fast responses - much appreciated.

I did some reading of the threads suggested and (not knowing what 2T was) I can see that the impact of being 2T appears to be minimal from Zebo's "real world" testing.

Also I am planning to run 4 slots 4 x 1 GB OCZ

The guy is recommending OCZ Platinum but I also read in the other thread that the Value stuff is nearly as fast.

thanks,

Dan.

Before you buy, are you going to use WinXp 32 bit? If you are, you will only be able to access 3.(something)GB of the ram. The new E stepping athlon64s can remap the memory address to overcome this, but it isn't always successful. 4GB is an OS limitation, and it is difficult to overcome (technically it is an addressing limitation).

If you are running a 64-bit OS (Linux/XP-Pro 64/Vista 64) you can use more than 4gb without problems. But then there are the limitations with mainstream software availability (linux) and driver availability (XP-Pro 64) and beta-OS (Vista 64).

Research hard before you go 4gb.

 

[allanon1965]

I have 2 Athlon 64 systems in the house, one for me , one for the wife, both have all 4 ram slots filled with 4X512mb dual channel ram, one is a 3000+winchester and the other is a venice. both systems are running at PC3200 at 2T, this was confirmed by everest and cpu-z....so I dont understand what you are saying about it only running at PC2700?

 

[Some1ne]

In theory your winchester should not be doing DDR400 with 4 slots filled, it should be going at DDR333. My winchester won't work at all if I populate all 4 slots.

 

[Matthias99]

Originally posted by: evilharp

Originally posted by: prosserd
hi,

Thanks very much for the (very) fast responses - much appreciated.

I did some reading of the threads suggested and (not knowing what 2T was) I can see that the impact of being 2T appears to be minimal from Zebo's "real world" testing.

Also I am planning to run 4 slots 4 x 1 GB OCZ

The guy is recommending OCZ Platinum but I also read in the other thread that the Value stuff is nearly as fast.

thanks,

Dan.

Before you buy, are you going to use WinXp 32 bit? If you are, you will only be able to access 3.(something)GB of the ram. The new E stepping athlon64s can remap the memory address to overcome this, but it isn't always successful. 4GB is an OS limitation, and it is difficult to overcome (technically it is an addressing limitation).

If you are running a 64-bit OS (Linux/XP-Pro 64/Vista 64) you can use more than 4gb without problems. But then there are the limitations with mainstream software availability (linux) and driver availability (XP-Pro 64) and beta-OS (Vista 64).

Research hard before you go 4gb.

Just to note: Windows can use all 4GB of RAM just fine. However, no single process can use more than 2GB of RAM (or 3GB with the /3GB switch turned on) unless it supports PAE (this is mostly used by server applications like databases). If your intent is to make a single program (like a game) run real fast, more than 2GB of RAM isn't going to help much. If you want to multitask a lot of demanding programs at once, it will help tremendously. With 64-bit apps running under a 64-bit OS, this is not a problem.

As far as this sales guy: run far, run fast. A64s run a hair slower with all 4 banks populated (unless you have the very latest CPUs and are able to force 1T mode successfully), but he's just full of it.

 

[n7]

As has been mentioned, running 4 GBs with a 32-bit OS will be a waste in many cases.

Honestly, even with 64-bit i have this feeling you won't need that much.

Why exactly do you need 4 GB of RAM ?

 

[allanon1965]

well Some1ne, I dont know what to tell you except that its running at 2T and DDR400 speeds with 4X512 dual channel KingMax SuperRam PC3200, with the KN1 Extreme MB by ECS, I will say this, when it was loaded initially it did default to 333, however after testing it and realizing it was doing that, all I did was manually set it at 400 and then tested again and it was running at 400 speeds...its using the NF4 chipset. What Motherboard and chipset are you using?

 

[Arcanedeath]

Officaly Winchester and older A64 cores default to DDR333 @ 2T when 4 Double sidded dimms are used, however many Winchester and even some older cores could run at DDR 400 @ 2T w/ 4 DS dimms, buts thats basicly just overclocking and it was luck of the draw if you got a memory controler and motherboard that could handel these speeds.

 

[Some1ne]

I have an MSI K8N Neo4 Platinum, so it's an nforce4 as well. One other source of problems may be that I was mixing Corsair PC4000 with Geil PC3200 RAM, although I can run just fine with 1 Corsair and 1 Geil, in single or dual-channel setups, it's only when I try all 4 that things refuse to work.

 

[allanon1965]

you should try getting matched dual channel ram, bet you would be able to go 400 then....i dont buy the overclocking bit, how is it overclocking when the ram is PC3200? all i am doing it running it at its rated speed...

 

[prosserd]

hi,

Why do I need 4 GB? Well I don't REALLY *need* it but I want it - to help reduce disk swapping and memory related stability problems. I work as a computer programmer by trade and I easily manage to max out my work system which runs 2 GB of RAM and has the swap setup nicely (non fragmented, properly sized).

I am writing a forex trading robot (in Java) that must stay up 24hr/5days - this program could get quite intensive, memory wise, as it matures into trading stocks and futures (I don't want to stop it during the 5 day period as it works off streaming data and missing out on trades could cost me more than the PC).

I also plan to use it for various other tasks like browsing, burning, trading system testing and an occassional game (on the 2 days when it isn't running).

Being a computer programmer, I don't quite understand a lot of the hardware lingo being discussed here - but i'm learning as I go

This is what I planned to get - open to any advice though... keeping in mind I have a limit to my budget Goals are quietness, reliablility and performance (like most people).

Case: Antec P180 Performance One
Power: Antec Phantom 500
Mobo: DFI LanParty UT NF4 Ultra-D
CPU: Athlon 64 X2 4400+
Cooler: Zalman CNPS7000-ALCU
RAM: OCZ Platinum PC3200 EL DC DDR 2 GB x 2 (maybe Value)
Disk: WD Caviar 250 GB 7.2krpm SATA2
GFX: Gigabyte NVIDIA GeForce 6600 256MB PCIE
Opt1: Pioneer DVR-110D x16 Dual Layer DVDRW
Opt2: Samsung SH-D162 x16 DVD-ROM
FDD: Panasonic 1.44
Mon: Viewsonic VX924 19"

Dan.