Features and Benefits

For those who are wondering, yes this board has some RAM on it but it is not the X-RAM. A few users have reported that their X-Fi's have the X-RAM but this one does not. It is a simple Samsung 2 Mb RAM chip onboard. If your X-Fi memory says MT on it, then you have the X-RAM.

There are four distinct flavors of X-Fi, the Xtreme Music, Platinum, Fatal1ty and the Platinum Pro. They all have the same basic features. The exception is the Xtreme Music, which is the only X-Fi not to come with an external breakout box. The X-Fi Xtreme Music is also the least expensive at $129 USD.

They will all be using PCI and not PCIe. Despite what Creative has claimed about PCIe latency, I think that the X-Fi APU was designed strictly for PCI and not PCIe. Creative may revise or use a bridge chip on the X-Fi for PCIe but I think that would be very costly.

For the X-Fi, Creative designed a new DSP chip, the CA20K1. This is a complex, programmable and parallelized monster.

According to Creative, it is very flexible in signal routing internally, with 4096 audio 'ring' channels to use. While it can output only 128 channels, each of those can have 8 simultaneous effects applied in real-time. Creative says that it took a software-style design rather than a pipeline design that we see for video cards and CPUs. We'll get to the software in a bit but first let's have a look at the Ringu from Creative:

An O-chem breakthrough, Creative invents the first APU powered with organic chemistry.

It is hard to tell if the new architecture is in the chip, in software, or both. DSP's, by their nature, are highly programmable so I would not be surprised. Creative mentions that the ring architecture is flexible enough so that audio streams are only routed to where they are needed, so that you don't have every stream go through the SRC or DSP if it doesn't need to. Let's hope it doesn't have anything to do with Token ring.

Basically, not counting I/O portions of the chip, the two most important 'bubbles' are the DSP and the SRC. The SRC can do a lot of math, about 7 gigaflops worth. While it is hard to test the chip for hard numbers like that, this is impressive. I also haven't read anything that directly states it, but I assume that internally the X-Fi operates at 24 bits and 192 kHz, which is the highest resolution currently available.

Take a look at the graph below.

What the X-Fi does is a fairly clever three step process, and actually conserves on computation. Creative states that the X-Fi has the quality of a 256-order FIR (finite impulse response filter) at the cost of a 100-order one. It first takes the stream to be converted and multiplies by two. Then it is multiplied by a special ratio, then upsampled to 192 kHz. Finally the audio stream is divided by four to give you the desired sample rate. Creative points out that this process is so accurate that it can be done multiple times without any accumulation or rounding errors affecting the final output.

At any rate, Creative assures us that any sonic degradation will not come from the SRC, but from the DAC's!

There are a lot of specialized units on the APU, but if there are audio chores that can't be done with one of them, you still need a programmable DSP to take up the slack. The X-Fi's DSP 'quartet' can do four tasks at once, which should help out the developers nicely. I wonder how easy it would be to create 'shaders' for audio that could run on the DSP…

Let's take a look at the hardware.