I had seen Gigabyte's i-RAM when it was displayed at Computex Taiwan last year and now Gigabyte has started supplying it North American consumers. i-RAM is a PCI card that has four slots for DDR SDRAM memory sticks and can be used as a hard drive once connected to the motherboard via a SATA cable. The gain with i-RAM is incredible speed compared to any traditional hard drive or even your WD Raptor hard drive. Since it is seen as a normal Serial-ATA hard drive to your motherboard's BIOS, you can actually RAID two or more of them. There are, however, several drawbacks. The RAM slots are tilted so they don't interfere with nearby expansion cards and therefore the i-RAM won't work with certain DDR sticks with heatspreaders. Also, i-RAM keeps the memory "alive" on each DDR slot with the use of an onboard battery, which can only power four sticks of RAM for around ten hours. This means you shouldn't really store vital information on it. Another drawback is that you are limited to four slots. Also it is 150 USD only for the card, you still need to provide your own memory. If you are looking to make that speed demon machine, it might be worth taking a look at. Some of the benchmarks are unbelievable.
While tight DIMM spacing limits compatibility with thicker heat spreaders, it's not a major concern, because it's unlikely you'll want to waste high-end memory on the i-RAM. You see, the i-RAM's Serial ATA controller is limited to 150MB/s transfer rates, creating a bottleneck that will constrain performance long before memory speeds or latencies enter the picture. In fact, even DDR200 memory has ample bandwidth to saturate the i-RAM's Serial ATA interface.