RAM latency and the A64

[blackpool9]

I'm preparing to upgrade from an Athlon XP 1800+ to an A64. I've pretty much decided to go Socket 754 3200+ with either the Asus or MSI Neo mobo and use the couple of hundred in savings over the S939 to upgrade my 9800 Pro in a couple of months. The last thing I'm agonizing about is the RAM.

It looks like some of the mobo manufacturers have been able to bypass the AMD specs that limit the A64 to a maximum of three banks of RAM chips at DDR400. So the next issue is latency.

How important is latency going to be in performance with the A64? Is there any appreciable difference in current applications between 1GB of RAM running at 3-3-3-8 vs. 2-3-2-6? Is it worth the extra $100 or so to get the lower latency modules?

My upgrading cycle for CPU and mobo is usually about 2 to 3 years, so this config will need to last me a while. And I'm not exactly swimming in money, so if I can save $100 without hurting performance, I'll go high-latency. But if there's a significant performance advantage to the faster RAM, I'll go with that.

 

[TheBDB]

I doubt you would ever see anything more than a 5% difference in performance.

 

[StrangerGuy]

Originally posted by: TheBDB
I doubt you would ever see anything more than a 5% difference in performance.

I think it may be even less than that.

 

[DAPUNISHER]

I agree with the others, while timings do seem to show respectable gains in tasks like SuperPi, ScienceMark, DC projects, for gaming they just aren't essential and do not justify the price premium. BTW, I suggest the 512mb cache model of the 3200+ as it's clocked@2.2ghz.

 

[StrangerGuy]

Originally posted by: DAPUNISHER
I agree with the others, while timings do seem to show respectable gains in tasks like SuperPi, ScienceMark, DC projects, for gaming they just aren't essential and do not justify the price premium. BTW, I suggest the 512mb cache model of the 3200+ as it's clocked@2.2ghz.

:Q

 

[sisooktom]

It's nowhere near worth it. As far as I can tell, low memory timings are for people who just assume it's better because it costs more. There's an article at Tom's that pretty much confirms that, at least for the A64, memory timings are almost completely irrelevant.

Edit: Here's the link. http://www.tomshardware.com/motherboard/20040119/index.html Notice how the timings do play a much larger role with Intel chips. This really speaks to the quality of the A64 design in my mind.

 

[DAPUNISHER]

LMAO! My bad! We'd all be scurring for a 512mb cache CPU eh?

 

[StrangerGuy]

Originally posted by: DAPUNISHER
LMAO! My bad! We'd all be scurring for a 512mb cache CPU eh?

I don't even think that the 512mb cache CPU will even fit into the 300mm wafers.

 

[blackpool9]

Originally posted by: sisooktom
It's nowhere near worth it. As far as I can tell, low memory timings are for people who just assume it's better because it costs more. There's an article at Tom's that pretty much confirms that, at least for the A64, memory timings are almost completely irrelevant.

Edit: Here's the link. http://www.tomshardware.com/motherboard/20040119/index.html Notice how the timings do play a much larger role with Intel chips. This really speaks to the quality of the A64 design in my mind.

Wow, that was just the kind of benchmarking comparison I was looking for. Don't know how I missed it when trolling Tom's. I guess because it's about 6 months old I didn't go back far enough.

The benchmarks seem to indicate not much more than a 1 or 2% increase in performance with the lower-latency modules in gaming. A bigger difference when encoding audio or video, but since I've already got my entire CD collection on my hard drive, I only need to rip audio once every month or two when I buy a new CD. Looks like as long as I buy brand name memory and a mobo that can run two 512MB sticks at DDR400, I'm good.

Thanks for the help, everyone!

Cheers!

 

[Markfw]

Well, unless things have changed, all the posts I have seen on system problems on the Athlon64 platform were due to cheap or high latency memory. I personally had problems with OCZ, and others. Also, running more than one stick. Mushkin PC3200 level1 minimum I recommend.

 

[Cerb]

Originally posted by: TheBDB
I doubt you would ever see anything more than a 5% difference in performance.

Quite a bit less than that.

 

[txxxx]

Originally posted by: Markfw900
Well, unless things have changed, all the posts I have seen on system problems on the Athlon64 platform were due to cheap or high latency memory. I personally had problems with OCZ, and others. Also, running more than one stick. Mushkin PC3200 level1 minimum I recommend.

Wasnt this something to do with the CPU, booting up with a command rate of 1t instead of 2t?

And this was fixed lately on latest revisions of CPUs?

 

[Bar81]

That's a completely different issue. The A64 memory controller is picky, you need to use good quality low latency RAM to ensure no problems. Otherwise, it's the luck of the draw.

 

[sisooktom]

Most memory issues I've heard about on A64 systems are the fault of the board, not the chip.

 

[blackpool9]

The Athlon 64 specs only allow for three banks (one double sided and one single sided stick, or three single sided sticks) of RAM at DDR400. That's the source of many of the system issues. Some mobo manufacturers have been able to overcome AMD's restrictions and run 4 banks at DDR400. The S939 chips don't have this problem because they run in dual-channel mode.

That's why I'm trying to be so thorough about this. I don't want to have to buy a single 1GB stick, as there's a significant premium in price against a pair of 512s. If I have to lay out an extra $100 on a single 1GB stick in order to ensure compatability at the rated memory speed, I'd rather use that money toward the S939 Athlon 3500+ and hold off on the video upgrade until November or so. I'd like to be sure that whatever memory I get will run in my mobo at the rated speeds and latency.

Anyone out there with the MSI K8N Neo Platinum or the Asus K8V SE Deluxe that are currently running more than three banks of RAM at DDR400?

 

[CrucialLabs]

The only thing you are really gaining when buying a 1gig module is it takes up less real estate. You will have an extra slot for more memory. If 2 single sided 512s will work then I would go with them. Crucial has some good stuff.

 

[dheffer]

I have a chaintech k8t800 in the mail, will it support my 2 x256mb pc3200 kit that i have? Its dual sided. If not im gonna be pissed

 

[DAPUNISHER]

Originally posted by: dheffer
I have a chaintech k8t800 in the mail, will it support my 2 x256mb pc3200 kit that i have? Its dual sided. If not im gonna be pissed

It'll be fine, relax and enjoy your new toy brudda

 

[dheffer]

haha well good, im thinking about upgrading to some OCZ Enhanced Latency Series Dual Channel Gold 184 Pin 512MB(256MBx2) DDR PC-4000 to try and push my 2800+ retail as close as i can get to a 3000+. *Crosses fingers*. Too bad my mobo blows, stupid unlocked pci/agp