Hey Zyg since we are dreaming anyway... Why not have a biological DNA based quantum CPU with infinite throughput and can scale it's bandwidth at will by evolving. Who needs RAM? Just have a near infinite level 1 cache connected quantum locked qibits directly embedded in the CPU and cache. May as well take advantage of quantum mechanics and stack infinite bits on top of each other, accessed by multiplexing the multiverse. With this kind of settings our timings should be as close to 0-0-0-0 as possible. Since it's infinite, we don't really need a HDD either. Who needs a display? Have it wirelessly resonate with dorsal and ventral streams in order to bypass any need for a display, you will sense it much as you effortlessly sense vision, sound, and any other senses. Or perhaps we should have it resonate straight in to your short term memory? Our infinitely powerful quantum dna CPU which multiplexes the multiverse should be enough to handle GPU calculations, after all, this is a system that can perform any instruction in a single cycle - well since it is a quantum dna computer, it's probably analogue and asynchronous in the first place, so it doesn't even have cycles. If for some strange reason we can't perform the action instantly, we can always just leverage our infinite universes and spawn a second, third, or billionth processor to help us out. I'm not sure the ramifications of starting new threads in alternate universes whilst using quantum computations, but I'm sure with this much power we can work it out. Naturally, such a computer would be controlled directly through thought by way of phase locked particles.
Oh yeah, and because this is a dream computer and all, the entire thing has no physical structure, it is composed entirely out of energy - in the form of vibrations in existing mass. In other words, we can project this computer on to a physical structure - for example it could be projected on to your hand, allowing you to take it with you wherever you go. And because we all love convenience, the best place to project it is directly in to your short term memory, thus removing the need to resonate information back in to your brain, removing whatever kind of display latency we would otherwise have.