In K8 Athlon64..definately BH5 pwn it due to higher memory bandwidth efficiency due to Tight timing. Anyway..on K7..it different story. Since UCCC can do 260-270FSB easily at low vdimm. And yet...you can dual channel the UCCC easily and bring up the bandwidth efficiency above what a BH5 can offer u.
512x2 BH5 at DDR500 5-2-2-2.0 Single Channel 1T will give u around 3700mb/sec bandwidth.
512x2 BH5 at DDR450 5-2-2-2.0 Dual Channel 1/2T will give you only 3400mb/sec bandwidth.
512x2 UCCC at DDR500 8-3-3-3.0 Dual Channel 1T will give u up to 3800mb/sec bandwidth.
512x2 UCCC at DDR500 8-3-3-3.0 SingleChannel 1T will give u up to 3400-3500mb/sec bandwidth.
If you can get ur Barton run at DDR540-550 on UCCC dual channel...i guess BH5 will be totally pwn by it by 10-15% performence margin.
Believe it or not..try it yourself. That what i can help u based on my experience. I already retired K7 for almost 1/2 years.

Running Dual Channel 15-5-5-3.0 with 1/2T on K7 offer performence greater then 5-2-2-2.0 Single Channel 1T. It because under DC the extra bandwidth in too big for the K7 Archtitecture to handle and hence it will use it to squeze the ram to perform at higher efficiency up 95-96% under any timing.