SDRAM bank interleave benchmarks

[hurtstotalktoyou]

Hey, all. I just ran some benchmarks for my own curiosity, and I thought I'd post them here on the off-chance that anyone cares.

Until today, I had never heard of "bank interleave" for SDRAM and DDR SDRAM. When I saw it as an option in my BIOS, it looked like some kind of dual-channel setup, but apparently that's not at all what it is. Bank interleave can be used on a single DIMM (or multiple DIMMs), and comes in flavors of 2-way and 4-way. Bank interleave is apparently out-of-date, but still available on older systems, including the Athlon XP rig in my bedroom.

So, I decided to run some benchmarks comparing standard non-interleave performance to 4-way interleave. Here's my test setup:

Athlon XP 1800+ Thoroughbred (B0) @ 1.84GHz
MSI KT3 Ultra-ARU w/FSB @ 294MHz
256MB (2x128MB) PC3200 DDR SDRAM @ 362MHz
Asus AGP V3800 Ultra Deluxe (nVidia TNT2)
80GB Western Digital WD800JB

And here are the tests I performed:

1. dBPowerAmp 10.1: 72:17 FLAC-8 to mp3 (160 kbps ABR)
2. WinRAR 3.40: 323MB iso image to RAR image
3. TMPGEnc Plus 2.58: 42:47 DivX 5.2.1 to DVD-quality MPEG-1

And here are the results:

DMC 10.1
no interleave: 330 sec.
4-way interleave: 320 sec.
performance increase: 3.13%

WinRAR 3.40
no interleave: 432 sec.
4-way interleave: 415 sec.
performance increase: 4.10%

TMPGEnc Plus 2.58
no interleave: 1615 sec.
4-way interleave: 1574 sec.
performance increase: 2.60%

So, as you can see, the performance is minimal, but still makes a difference. WinRAR showed the greatest benefit, which is a shame since I use it the least. DMC was affected, too, and I do use that considerably more. I regret to admit that the video editing application, TMPGEnc, which is what I use the most of all, only cleared a 2.60% performance boost.

CONCLUSION: Bank interleave is only available on older systems which cost very little. That means your money is probably better spent on a faster CPU, where a mere five dollars can spell the difference between a Thunderbird and a Thoroughbred. Bank interleave should therefore be left out of the budgeting equation. However, when comparing two motherboards at the exact same price point, look for bank interleave to help tip the scales. Moreover, if you have an older system and never bothered to check, go into your BIOS and make sure it's turned on if supported.

 

[Idontcare]

I thought bank interleaving is an automatic thing on all new mobos, meaning you can't turn it on or off but rather it is always simply on.

I noted about a 4-5% bump in winrar MB/s when I populated all 4 dimm sockets (despite my relaxing the timings to add stability), the only explanation I got from scouring the web was that the additional performance gain from automatic interleaving compensated for the bandwidth lost from relaxing my timings, netting out in the positive territory at the end of the day.

And TMPGEnc FTW!