DDR Memory Bandwidth Efficiency Question at DVinfo.net

John Britt · January 10th, 2005, 12:03 PM

I just built a new system w/ an ASUS P4P800-E Deluxe motherboard (865PE chipset), 3.2E Pentium 4, and 1 GB RAM (2 sticks of 512MB DDR 400 RAM).

Running SiSoft Sandra 2005 lite, I see my Int. bandwidth at 4338 MB/s and Float at 4314 MB/s. This is with many unnecessary Services turned off. According to Sisoft, this is about 500 MB/s less than their benchmark for the 865PE w/ DDR 400 RAM. It also says that the memory is only running at about 68% efficiency.

What sort of bandwidth efficiency should I expect from my system? I know that Intel has claimed that 1 GB DDR 400 should hit about 8000 MB/s, but I assume that's pie-in-the-sky. If I should expect more, though, what can I do increase memory performance? (keeping in mind that I've shut off unneeded service and that there few apps installed on this machine)

Some real-world tests definitely show this machine to be faster than my 1.9Ghz P4 w/ 768 MB RDRAM at some tasks. In some After Effects tasks, the new build runs 2x-5x faster (based on fps when rendering a timeline by hitting the spacebar). Other AE tasks only show a slight improvement (say, 1.5x faster).

Some apps, though, don't seem any faster at all, such as rendering a 3D scene in Bryce 5 (that said, this machine won't be used for anything but Premiere/AE/Photoshop, but I want to upgrade the older computer soon, as well). So real-world looks OK for some things, not others. But what about the benchmark numbers?

John Lee · January 10th, 2005, 12:12 PM

You could mess with your RAM timing settings in your mobo BIOS if you know what the safe values are. Also, what brand of RAM are you using? That can make a difference. And 500 MB/s, although it sounds like a lot is only a 10% difference at the speed you have.

Also, Bryce 5, if I remember correctly is very CPU intensive. I upgraded my RAM a year ago and I remember bryce didn't run much faster. Some programs just don't respond well. Bryce is historically bad I believe when it comes to system efficiency. But the interface is sweet in my opinion.

John Britt · January 10th, 2005, 12:15 PM

It's Kingmax (inexpensive, yes, but had good user reviews).

The 500 MB/s isn't catching my attending as much as the 68% efficiency. Is that typical efficiency or am I way off? Google didn't seem to help much in answering the question, so either this is rare, or expected, I assume...

EDIT: and to clarify, the memory on my older computer is suppossedly operating at 75% efficiency, according to SiSoft.

John Lee · January 10th, 2005, 12:28 PM

I'm not too familiar with SiSoft Sandra, I haven't used it in awhile.

I have an ASUS P4PE at home, and I can run the SiSoft on it when I get back there. Also, you should check your FSB setting in your BIOS if you haven't yet. It's probably on the right setting, but if you are running at a 533MHz FSB that could be the problem.

If you have enough cooling you can step up your FSB a few MHz, but the P4 E edition runs pretty hot. I assume you're probably familiar with the anandtech.com and sharkyextreme.com boards. If not, you should try posting there, the people know a lot about getting the most out of PC's.

John Britt · January 10th, 2005, 02:36 PM

FSB is running at 800 MHz. Checking the BIOS, everything looks fine, and using ASUS's Probe (which basically tells you what the BIOS does), everything looks in order. It does tell me that at idle, with no apps running, that physical memory usage is between 17%-20% (17% after I turned off some services, 20% at default).

I tried to target anandtech when googling, but I didn't try sharkyextreme -- I'll look around there.. I just hate being the newbie with the first post about how he's an idiot...

Thanks for your help...

Glenn Chan · January 13th, 2005, 02:23 AM

You could also measure memory bandwidth with memtest.
mestest86.org

You need to decide on creating a bootable CD or floppy. The program will create a bootable CD image, or a bootable floppy.

2- Did you buy PC3200 RAM? PC2700 will run slower... you can overclock it to run at PC3200 speeds and test with memtest86 (I also recommend you test with Prime95 if you want to be doubly safe... memtest is like 95% accurate).

January 10th, 2005, 12:03 PM	#1
John Britt Major Player Join Date: Sep 2003 Location: Atlanta, GA Posts: 621	DDR Memory Bandwidth Efficiency Question I just built a new system w/ an ASUS P4P800-E Deluxe motherboard (865PE chipset), 3.2E Pentium 4, and 1 GB RAM (2 sticks of 512MB DDR 400 RAM). Running SiSoft Sandra 2005 lite, I see my Int. bandwidth at 4338 MB/s and Float at 4314 MB/s. This is with many unnecessary Services turned off. According to Sisoft, this is about 500 MB/s less than their benchmark for the 865PE w/ DDR 400 RAM. It also says that the memory is only running at about 68% efficiency. What sort of bandwidth efficiency should I expect from my system? I know that Intel has claimed that 1 GB DDR 400 should hit about 8000 MB/s, but I assume that's pie-in-the-sky. If I should expect more, though, what can I do increase memory performance? (keeping in mind that I've shut off unneeded service and that there few apps installed on this machine) Some real-world tests definitely show this machine to be faster than my 1.9Ghz P4 w/ 768 MB RDRAM at some tasks. In some After Effects tasks, the new build runs 2x-5x faster (based on fps when rendering a timeline by hitting the spacebar). Other AE tasks only show a slight improvement (say, 1.5x faster). Some apps, though, don't seem any faster at all, such as rendering a 3D scene in Bryce 5 (that said, this machine won't be used for anything but Premiere/AE/Photoshop, but I want to upgrade the older computer soon, as well). So real-world looks OK for some things, not others. But what about the benchmark numbers?

January 10th, 2005, 12:12 PM	#2
John Lee Regular Crew Join Date: Nov 2002 Location: Silver Spring, MD Posts: 152	You could mess with your RAM timing settings in your mobo BIOS if you know what the safe values are. Also, what brand of RAM are you using? That can make a difference. And 500 MB/s, although it sounds like a lot is only a 10% difference at the speed you have. Also, Bryce 5, if I remember correctly is very CPU intensive. I upgraded my RAM a year ago and I remember bryce didn't run much faster. Some programs just don't respond well. Bryce is historically bad I believe when it comes to system efficiency. But the interface is sweet in my opinion. __________________ John Lee Levelse7en@gmail.com

January 10th, 2005, 12:28 PM	#4
John Lee Regular Crew Join Date: Nov 2002 Location: Silver Spring, MD Posts: 152	I'm not too familiar with SiSoft Sandra, I haven't used it in awhile. I have an ASUS P4PE at home, and I can run the SiSoft on it when I get back there. Also, you should check your FSB setting in your BIOS if you haven't yet. It's probably on the right setting, but if you are running at a 533MHz FSB that could be the problem. If you have enough cooling you can step up your FSB a few MHz, but the P4 E edition runs pretty hot. I assume you're probably familiar with the anandtech.com and sharkyextreme.com boards. If not, you should try posting there, the people know a lot about getting the most out of PC's. __________________ John Lee Levelse7en@gmail.com

January 10th, 2005, 12:15 PM	#3
John Britt Major Player Join Date: Sep 2003 Location: Atlanta, GA Posts: 621	It's Kingmax (inexpensive, yes, but had good user reviews). The 500 MB/s isn't catching my attending as much as the 68% efficiency. Is that typical efficiency or am I way off? Google didn't seem to help much in answering the question, so either this is rare, or expected, I assume... EDIT: and to clarify, the memory on my older computer is suppossedly operating at 75% efficiency, according to SiSoft.

January 10th, 2005, 02:36 PM	#5
John Britt Major Player Join Date: Sep 2003 Location: Atlanta, GA Posts: 621	FSB is running at 800 MHz. Checking the BIOS, everything looks fine, and using ASUS's Probe (which basically tells you what the BIOS does), everything looks in order. It does tell me that at idle, with no apps running, that physical memory usage is between 17%-20% (17% after I turned off some services, 20% at default). I tried to target anandtech when googling, but I didn't try sharkyextreme -- I'll look around there.. I just hate being the newbie with the first post about how he's an idiot... Thanks for your help...

January 13th, 2005, 02:23 AM	#6
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	You could also measure memory bandwidth with memtest. mestest86.org You need to decide on creating a bootable CD or floppy. The program will create a bootable CD image, or a bootable floppy. 2- Did you buy PC3200 RAM? PC2700 will run slower... you can overclock it to run at PC3200 speeds and test with memtest86 (I also recommend you test with Prime95 if you want to be doubly safe... memtest is like 95% accurate).