Source: Tom's Hardware UK – Keywords: Phenom_9700, Spider_Platform, 790FX
Categories: Hardware
Technology II - Branch Prediction, Stack Counter
Object-oriented programming languages such as C++, Delphi and Java cause the most problems for branch prediction units. When branching occurs in assembly code, the question is not only whether or not a jump occurs, but also what code module the jump points to. AMD has analyzed the current crop of compilers and tweaked its branch prediction logic to increase the likelihood that the processor chooses the right branch/path. This allows many programs to execute faster.
When program code is executed, its memory address in the stack, which is basically a buffer for data, is stored in the ESP register. Until now, while decoding x86 instructions the processor had to manage the micro-ops for manipulating the ESP register on its own, which required processor time. AMD’s Phenom now comes with a sideband counter that monitors the stack independently and automatically adjusts the ESP register. Thus, the instructions for updating the ESP no longer have to be executed, speeding up overall program execution.
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I'd rather have a slower processor but not have to rebuy the 3 of the most expensive components (CPU, mobo, and RAM) every time I want to upgrade something. That's why I've stuck with AMD for the last few years. Can't wait to drop a couple of Phenom FXs in to my 4x4 platform and have 8 processing cores.
What is going to happen when AMD shortly moves to 45nm processors with DDR3 memory controllers?
unless AMD are going to put both DDR2 and DDR3 memory controllers on their 45nm processors or make them in both DDR2 and DDR3 versions then you will have to change you're ram, motherboard and processor to go 45nm.(that didn't happen with intel)
Unless motherboard makers put both DDR2 and DDR3 slots on current boards although the latter wouldn't be supported until 45nm come in.(can't see that happening though).
I think these chips have more to come, thats an engineering sample and the mainboards got a chipset with undeveloped drivers.
I say give it a month for the nvidia chipset....... and retest.
I can see why they need 4x Crossfire boards given the lack luster performance of the new ATI cards... ATI seem to be struggling since their Cope-de-grace with the X19xx series...
AMD clearly has a good design (architecture) but the process technology is their achilles heal. They need 4Mb+ L3 cache, high K transistor process, and 45nm like yesterday!!
As a bit of an AMD fanboy (I'm on a dual Opteron rig just now) I hate to see whats happening to them now!!
Bob
P.S. But it will be better
Overall, I like the way AMD has gone for compatibility and performance. The price is phenomenal and the ease of implementation will ensure downtime during upgrades is kept to a minimum. It's easy to under-estimate just how hard that is to pull off.