AMD FX "Vishera" reviews info (again, after mod mistake)

[The Stilt]

This is awesome. Imagine if Amd sold fx-8350 with 95w tdp they be in a little better shape.

Hey stilt what's max stable 24/7 for yur 8350 1244pgn chip on Amd fx watercooler? What r temps?

I want a 8350 24/7 stable @ at least 5ghz....just curious if Its worth it to get one if these all in one systems like a corsair h100 or a antec kuhler 920 would do the job... Assuming I get a good batch number. Maybe ill get lucky like u guys

Gonna pluck this into my Crosshair 5

My 24/7 system is using a A10-5800K so I don?t really have 24/7 clocks for the FXs

Nowdays I'll always try to find the optimal balance between the efficiency and performance, not the absolute performance at all cost.

An example: FX-8350 requires 1.3750V for Prime95 stability at 4500MHz and 1.4400V at 4700MHz.

4500MHz
1.3750V
Estimated Pmax: 145.9W

vs.

4700MHz
1.4400V
Estimated Pmax: 167.1W

Difference in performance: 4.4%
Difference in power consumption: 14.5%

To maximize the balance of performance and efficiency I want the "golden ratio" to be =<2.0.
In the example above the power limit would be 158.7W, which means the chip must be able to do the 4.7GHz with 1.40V voltage.
In that case the increase in power consumption could be justified (difference in power 8.8%, difference in performance 4.4%).

Also keep in mind that a small 20W increase in CPU power consumption will increase the actual power consumption much more than that.
CPU VRM efficiency: 75% -> 26.7W
PSU efficiency: 90% -> 29.7W

I'll start to sound like a greenpeace rep now so better stop...


I have not tried the maximum Prime95 stable frequency yet on this chip, however I recon it is not that good.
This is an ultra high leakage part so the heat will become a issue very quickly.

Achieving 24/7 stability at 5.0GHz+ is not matter of how good your chip is, let alone the batch code of the CPU.
Each and every single one Vishera CPU ever manufactured will reach 5.0GHz 24/7... with sufficient cooling.

The term sufficient varies. It is anything between 10C liquid to LN2.

Only one thing is certain: 24/7 stable 5.0GHz or higher cannot currently be done on normal air or watercooling.
Because of heat <=> power consumption (motherboard).

A rough estimate what the 24/7 stable 5.0GHz would require:

• 190W+ cooling capacity at <40C CPU die temperature
• 60W+ cooling capacity for CPU VRM
• 130A+ constant CPU VRM current capability

The highest 24/7 Prime95 stable frequency I have reached on 8-core Vishera is 4.9GHz.
Cooled with AMD FX watercooler, fans running at 100% DC (ear protection required) and in 21C ambient.
The CPU *might* have been a "airbender" special (with special seasoning)