This approach has no future perspectives. Four-channel configurations seem senseless from the economical point of view, while FSB frequency of Pentium 4 is unlikely to grow higher in near future, at least not until DDR II is ready.

Of course, this approach is not free from some drawbacks. In fact, there is only one drawback: the price. Mainboards will cost more and the user will have to buy two memory modules, since single-module configurations will no longer work fine. It's hardly a nice thing, but the inevitable price reduction will eliminate this disadvantage almost completely.

The upcoming VIA PT800 chipset supporting QBM will hardly be a better-value solution. QBM PC3200 modules deliver the same 6.4GB/s in one-channel configurations. The mainboard can feature simple, 4-layer design. The price of the chipset isn't greatly affected by integration of the QBM logic. But the memory modules themselves will cost a lot. By preliminary estimates, a QBM module will cost about $15 more than a DDR module of the same capacity and frequency. This may definitely kill other cost advantages.

Kentron appeals to the future and is quite reasonable about it: PC6400 DDR II modules will come into the market around the year 2005 and won't be compatible with current DDR modules. Take their pin difference as an example: 184 against 232. Kentron offers the same performance, but today and using current infrastructure. There are no compatibility issues: mainboards supporting QBM will also work with ordinary DDR DIMMs.

There is one more thing to be mentioned: Kentron's proposal also promises latencies reduction and stability growth thanks to QBM10 switches. The sample models show that QBM memory timings are at least no worse than those in DDR II, while signal lines volume is considerably reduced compared to current DDR modules. It means higher capacities and more DIMM slots than usual.

Overall, we have got an ambiguous situation. There are two approaches similar from the price point of view, but differing in everything else. The dual-channel DDR will provide 6.4GB/s bandwidth with current mass production modules, but it's impossible to increase the bandwidth any higher. QBM will yield the same 6.4GB/s, but with some future perspectives: two channels will deliver 12.8GB/s at a reasonable price. But for QBM to become popular, it's necessary that at least several big manufacturers supported this standard. And they don't really like experiments like that.

On the other hand, the situation is changing somehow. Remember the last Kingston's move with its overclocked DDR modules? The company has always been a pattern of solidity, but business is business: make money the way you can.

Kentron promised to sample 4.2GB/s QBM modules (based on PC2100 DDR) in December, with mass availability in the first quarter of 2003. Then it promised to launch PC2700 based 5.4GB/s models together with the arrival of Pentium 4 supporting 667MHz FSB. Now the plans have been corrected and Kentron promises to provide enough 6.4GB/s (PC3200) QBM modules in the second half of 2003. So, let's wait, although…

The short list of QBM Alliance members includes only one module maker. It's PNY Technologies, which is not a prominent player in the DIMM modules market. That's all. We can hardly hope for any changes in the near future. There are no serious reasons for DIMM makers to support QBM. They can't follow VIA in the Pentium 4 chipsets market: we all know how "strong" VIA feels there.

As for Intel, it all looks quite clear, too. The company has made its choice: they decided to support the dual-channel configuration. Intel won't support any of VIA's initiatives (and QBM is now VIA's initiative as well as Kentron's). And moreover, Intel's approach is quite competitive now, so the industry will preferably support it.

The summary is simple: QBM is an interesting, but doomed idea. In all probability, it will follow the fate of another interesting technology, VCM SDRAM, proposed by NEC, but completely ignored by the industry.