In our last CrossfireX article we performed a mix and match experiment, pairing up two RADEON 5870 from two different manufacturers and also with two different memory configurations to see whether they would play along nicely. The outcome was that in most of the applications tested, no problems occurred, however, in some of the synthetic benchmarks like FutureMark’s 3DMark Vantage, some of the test suites scored more like a single card. More importantly, we saw similar results in some of the games we tested. Needless to say that the potential root causes could have been anything from a system or CPU limitation to differences in the BIOS string and last not least the differences in memory space allocations that could wreak havoc on the performance. The bottom line, regardless, was that we didn’t recommend extreme mix and match because there may be some sleeping dogs that wake up just at the most inconvenient time or game play.

To look into the issues encountered more closely, we took a pair of uneven twins, that is ASUS RADEON EAH5850 and ASUS RADEON EAH 5850TOP, the first one following AMD’s reference design and the second one ASUS home-brew concoction of the 5850 series and teamed them up in CrossfireX. The default frequencies and the port configuration as well as the layout and cooling solutions of the two cards are about as different as one could build them within the same design constraints posed by the components but we did not really expect to find any major problems.

Solid state drives are becoming increasingly popular. The trend started with the enthusiast and early adapter community, and arguably, there were a few bumps and glitches. Some of the primary issues were simply caused by trying to squeeze solid state drives into an environment custom tailored towards hard disk drives, some other issues were insufficiencies on the SSD controller, particularly with respect to the exact workings of NAND flash.

In several earlier articles, we already covered some of the important aspects of flash memory cells and the inherent limitations caused by "Fowler-Nordheim" quantum-mechanical tunneling as programming and erase mechanisms. We also covered some of the system-level challenges faced by SSDs along with countermeasures implemented in the latest versions of operating systems or drivers to keep SSDs at a steady state of performance by proactively performing TRIM and garbage collection.

The one thing we have not covered yet is the heart and soul of NAND flash memory, that is, the organization of NAND flash, as opposed to for example NOR flash or any similar non-volatile memory, which is the reason for its cost effectiveness but also has some functional consequences in the form of read disturb and write disturb. Disturbing? On the surface, yes, but not if you drill down below the surface of the buzzwords to understand what you are actually talking about.