Intel's Sandy Bridge Architecture Exposed
by Anand Lal Shimpi on September 14, 2010 4:10 AM EST- Posted in
- CPUs
- Intel
- Sandy Bridge
New, More Aggressive Turbo
Lynnfield was the first Intel CPU to aggressively pursue the idea of dynamically increasing the core clock of active CPU cores while powering down idle cores. The idea is that if you have a 95W TDP for a quad-core CPU, but three of those four cores are idle, then you can increase the clock speed of the one active core until you hit that TDP limit.
In all current generation processors the assumption is that the CPU reaches that TDP immediately upon enabling turbo. In reality however, the CPU doesn’t heat up immediately - there’s a period of time where the CPU isn’t dissipating its full TDP - there’s a ramp.
Sandy Bridge takes advantage of this by allowing the PCU to turbo up active cores above TDP for short periods of time (up to 25 seconds). The PCU keeps track of available thermal budget while idle and spends it when CPU demand goes up. The longer the CPU remains idle, the more potential it has to ramp up above TDP later on. When a workload comes around, the CPU can turbo above its TDP and step down as the processor heats up, eventually settling down at its TDP.
While SNB can turbo up beyond its TDP, the PCU won’t allow the chip to exceed any reliability limits (similar to turbo today).
In addition to above-TDP-turbo, Sandy Bridge will also support more turbo bins than Nehalem/Westmere. Intel isn’t disclosing how much more turbo headroom we’ll have, but the additional bins are at least visible with multiple cores active. Current designs usually only turbo up one or two bins with all four cores active, I’d expect to see another bin or two there and possibly more in lighter load cases.
Both CPU and GPU turbo can work in tandem. Workloads that are more GPU bound running on SNB can result in the CPU cores clocking down and the GPU clocking up, while CPU bound tasks can drop the GPU frequency and increase CPU frequency.
Sandy Bridge as a whole is much more dynamic of a beast than anything that’s come before it.
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beginner99 - Tuesday, September 14, 2010 - link
AMD's been taking about fusion forever but I can't get rid of the feeling that this Intel implementation will be much more "fused" than the AMD one will be. AMD barley has CPU turbo so adding a comined cpu/gpu turbo at once, maybe they can pull it off but experience makes me doubt that very much.BTW, if it takes like 3mm^2 for a super fast video encoder I ask my self, why wasn't this done before?
duploxxx - Tuesday, September 14, 2010 - link
first or not, doesn't really matter.who says AMD need's GPU turbo? If Liano really is a 400SP GPU it will knock any Intel GPU with or without turbo.
If we see the first results of Anadtech review which seems to be a GT2 part it doesn't have a chance at all.
core i5 is really castrated due to lack of HT, This is exactly where liano will fight against, with a bit less cpu power.
B3an - Tuesday, September 14, 2010 - link
Even if AMD's GPU in Liano is faster, intels GPU is finally decent and good enough for most people, but more importantly more people will care about CPU performance because most users dont play games and this GPU can more than easily handle HD video. And i'm sure SB will be faster than anything AMD has. Then throw in the AVX and i'd say Intel clearly have a better option for the vast majority of people, it just comes down to price now.B3an - Tuesday, September 14, 2010 - link
Sorry, didnt mean AVX, i meant the hardware accelerated video encoding.bitcrazed - Tuesday, September 14, 2010 - link
But it's not just about raw power - it's about power per dollar.If you've got $500 to spend on a mobo and CPU, where do you spend it? On a slower Intel platform or on a faster AMD platform?
If AMD get their pricing right, they could turn this into a no-brainer decision, greatly increasing their sales.
duploxxx - Tuesday, September 14, 2010 - link
now here comes the issue with the real fanboys:"And i'm sure SB will be faster than anything AMD has."
It's exactly price where AMD has the better option. It's people " known brand name" that keeps them at buying the same thing without knowledge... yeah lets buy a Pentium.
takeulo - Wednesday, September 15, 2010 - link
hahahahah yeah i agree AMD is the better option at all if i have the high budget i'll go for Insane i mean Intel but since im only "poor" and i cant afford it so i'll stick to AMD and my money worth itsorry for my bad english XD
MySchizoBuddy - Monday, December 20, 2010 - link
how do you know Intel GPU has reached good enough state (do you have benchmarks to support your hypothesis). they have been trying to reach this state for as long as i can remember.your good enough state might be very different that somebodies else's good enough state.
bindesh - Tuesday, September 20, 2011 - link
Your all doubts will be cleared after watching this video, and related once.http://www.youtube.com/watch?v=XqBk0uHrxII&fea...
I am having 3 AMDs and 1 Intel, Believe me with the price of AMD CPUs, i can only get a celeron in Intel. Which cannot run NFS SHIFT. Or TIme Shift. But other hand, with AMD athlon, i have completed Devil May Cry 4 with decent speed. And the laptop costs 24K, Toshiba C650, psg xxxxx18 model. It has 360 GB SSD, ATI 4200HD.
Can you get such price and performance with Intel?
Best part is that i am running it with 800MHz cpu speed, with performance much much greater than 55K intel dual core laptop of my friend.
vlado08 - Tuesday, September 14, 2010 - link
Still no word ont the 23.976 FPS play back?