5 ms·
Please someone correct me if I'm wrong, but AFAICS the core voltage of the i9 1,52V. So with 254W, that thing really draws 167 amps? I guess every μΩ of resista
by deng 6y ago
Please someone correct me if I'm wrong, but AFAICS the core voltage of the i9 1,52V. So with 254W, that thing really draws 167 amps? I guess every μΩ of resistance counts here or the board just explodes?
- jeffbee 6y agoThat's already been a problem for a long time. When CPU speed changes the transient currents are ridiculous, and the dI/dt is bananas, too. This is one reason why a few generations ago Intel had to go with a fully-integrated voltage regulator. The mainboard people were unable to build good, efficient VRMs off-chip.
- eggsnbacon1 6y agoMaybe its not possible to regulate such a high current at gigahertz speeds off chip? The board traces and pins might have inductance high enough to negate smoothing capacitors at these speeds?
- jeffbee 6y agoYeah I mean there's no way a part on the other side of a CPU socket is doing anything in the gigahertz range. Those frequencies are covered by layers and capacitors in or on the package itself. What's hard about modern VRMs is being able to step from Icc(max) to zero while overshooting < 25mv, or the forward load step from nothing to ~200A in an instant without dropping. The specs are in Intel's VRxx docs (eg VR13).
- eggsnbacon1 6y agocan someone calculate the watts/meter^2 on this chip, for science? Eyeballing the chip, it looks like ~5cm^2? This would mean it puts out 500,000watt-meter^2 or about 50 times the heat of the surface of the sun. Do we have cameras fast enough to see this explode if the heatsink falls off?
- gruez 6y ago>This would mean it puts out 500,000watt-meter^2 or about 50 times the heat of the surface of the sun Where are you getting this figure? A random website[1] says the heat on the surface of the sun is 62,499,432 W/m^2. Also the die sizes are on page 2: 198.4 mm^2 for the 10 core part. Divide the total power (254W) by that and you get 1,280,236 W/m^2. [1] https://www.pveducation.org/pvcdrom/properties-of-sunlight/the-sun https://www.pveducation.org/pvcdrom/properties-of-sunlight/t...
- eggsnbacon1 6y agoexcellent thanks! And no that number was from a random website :) . Looking at it, I think its solar radiance at earth surface. 1000 watts per meter is way too low donno what I was thinking
- segfaultbuserr 6y agoThis is the CPU power density infograph you are looking for. https://i0.wp.com/semiengineering.com/wp-content/uploads/2014/04/Screen-Shot-2014-04-14-at-8.49.48-AM.png?resize=676%2C615 https://i0.wp.com/semiengineering.com/wp-content/uploads/201...
- eggsnbacon1 6y agoIts pretty funny that after 20 years we're off the right side of this graph by 100X right? Current chips are somewhere between "internal combustion engine" and "surface of the sun"
- segfaultbuserr 6y ago> I guess every μΩ of resistance counts More importantly, every μH of inductance counts. Running 200 A into the chip is not that difficult, the real difficulty is the high di/dt - how to maintain a nice regulated voltage when the current consumption suddenly raises from 10 A to 200 A within a few microseconds.
- segfaultbuserr 6y ago> μH It's a typo, should be nH. 1 μH is a huge value.
- blattimwind 6y agoThey do. CPUs tend to run at pretty high core voltages to achieve their high clock speeds compared to GPUs, so GPUs consume even more current: 300 W at ~1 V = 300 A. In AMDs case the CPU is supplied with a common core voltage that's regulated by a per-core ultra-fast LDO. There is also a power capacitor (mimcap) on the core die.