Archief - Vcore and vdimm with A64

Guys this is most important

If you run a high vdimm and a low vcore with E die etc you are running the risk of killing the cpu's. So if you have VX etc and you are not raising the vcore on your cpu you stand a chance of pumping a lot of current into the memory controller and causing permenant damage.

Im seeing people running $1k cpu's at default vcore and BH5 at 3.4V, this is a sure way to kill the cpu and is NOTHING to do with an issue on the board. If you are going to run high vdimm run a higher vcore also, and keep your CPU's ok.

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Micutzu zei:

First of all, the CPU doesn't have to do directly with the VDD, but with Vtt/Vref, wich should vary from 1.25 to 2V when you adjust the RAM from 2.5 to 4V. Maximum JEDEC Vdd voltage is 2.85V, and lowest voltage for A64 CPU's (CnQ activated) is 1.1V, so we know for sure that a difference of 0.325V between Vcore and Vtt is safe. This means that for a 1.35V Vcore voltage, we can have a safe Vdd of at least 3.35V, and for 1.5V Vcore -> 3.65V Vdd.
Probably the real danger is when those diodes go near the opening (conduction) voltage, wich should be ~0.6V for Si-based junction; if this is true, 1.35V Vcore and above 3.9V Vdd should kill the CPU instantly ... anyone wanna try ?

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Martin Cracauer zei:

Based on Micutzu's conclusion that 0.325 V differential should be safe (which I think makes a lot of sense), here is a small table listing what Vcore should be safe for which Vdimm:

Vdimm - Vcpu(min)
----------------------------
2.9 V --- 1.12 V (min)
3.0 V --- 1.17 V (min)
3.1 V --- 1.22 V (min)
3.2 V --- 1.28 V (min)
3.3 V --- 1.33 V (min)
3.4 V --- 1.37 V (min)
3.5 V --- 1.42 V (min)
3.6 V --- 1.47 V (min)
3.7 V --- 1.53 V (min)
3.8 V --- 1.58 V (min)
3.9 V --- 1.62 V (min)
4.0 V --- 1.67 V (min)

Absolutely NO WARRANTY for this. This is a knee-jerk approach based on loose findings we have. Use at your own risk.

And again, it is minimum safe CPU voltage based purely on the problem of voltage differential between CPU and RAM. The above table does not take any other voltage considerations into account. Or in other words: the voltage that is the minimum with regards to the Vdimm differential might already be over the upper limit of your CPU - and blow it up.

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Jort- zei:

ik stel voor van dit in de sticky te zetten

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duploxxx zei:

Can one thing be clarified here:
If I'm running an x2 4800 stock with Vcore 1.35V and have cool n' quite enabled which drops the Vcore to 1.1V, have my OCZ EL Platinum running with 2.65V is this a problem. Meaning when the cpu is running with 1.1V due to cool n' quite and the mem with 2.65V....is that a problem.
WHat the hell IS safe :doh:

duploxxx

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