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AMD FX-8370E and a 4 phase VRM (with heatsink)

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Sep 28, 2015
So here's the thing. I've been pretty happy with my system, running my Phenom II X6 1090T @ 3.7-3.8 GHz for the past year or so. Considering its age, the Phenom II is a very impressive CPU. Ever since I bought a GTX 1060 last fall, I've been able to most play games @ 1080p/50 FPS with almost everything except anti-aliasing turned on. However, the symptoms of I-want-an-upgrade-itis are real. A natural successor for the Phenom II would be something like an R5 1600, but I don't have the funds to build a Ryzen system at the moment. Besides, there still seem to be some issues with the CPUs and motherboards, so I'd probably wait until next year anyways. So, since the sensible option is not an option, I've set my sights on something some people would consider nonsensical: an FX-8370E.

Now, I think I know the two biggest arguments against the switch:

1. My motherboard has a 4-phase VRM and one simply does not use 8-core FX processors with weak VRMs, regardless of what the CPU support list says.
2. The FX-8370E is not much of a performance upgrade. In some workloads it's actually worse than the Phenom II.
3. The CPUs aren't even that cheap considering you can now buy a Ryzen CPU.

The first argument is why I'm considering an FX-8370E. My motherboard's VRM has been able to handle the Phenom II @ 1.4125 V, so even though voltage is only part of the story, I think the VRM might be able to hande the FX - at least at stock voltages (~1.2 V ?). Note that my CPU cooler blows air downwards at the motherboard and the VRM, the southbridge and the northbridge all have heatsinks, so things could be worse when it comes to cooling other components on the motherboard. The second argument is a tougher one. Single thread performance should in principle be better in the FX processor, at least if it's overclocked to the same 3.7-3.8 GHz I have on the Phenom II (might be achievable with near stock voltages, I'd probably turn Turbo off from the BIOS). In addition, the newer CPU supports a lot of instruction set extensions the Phenom II doesn't. I'd finally be able to run Timespy! However, in some cases the Phenom II might still perform better, as can be seen in these benchmarks. In the same article it can also be seen how the FX fares better in games, which at the moment is the main use I have for my computer. In any case there's a risk that my VRM will catch fire and there's a risk I won't see any benefits. However, the mere idea of trying is intriguing, which bring me to the third argument. It seems that a new FX-8370E would set me back around 120 e, which is not an insignificant amount of money to pay for something that has essentially been EoL for a few years and might not be much of an upgrade. However, if the new chip would keep me happy for, say, a year, then I think it might be worth it.

What I would like to know is this: Has anyone happened to have an E-series FX CPU running with a motherboard with a 4-phase VRM and if so, did you experience any VRM throttling or severe issues when overclocking (even with stock voltages)? Also, what about switching from a Phenom II to an FX-line CPU? I know some people have done it, but did you notice any clear benefits or did you instantly missed the Phenom II?


Beamed Me Up!
Jun 9, 2013
The PII out and out crushes FX at everything, unless you absolutely need 8 cores.
To match the performance of your PII at 3.8, the FX will have to be running 4.8
Not bloody likely on your board and cooling.


Oct 28, 2014
Wenatchee, WA
I know from personal experience that the fx-8350 and fx-8320 and fx-8370e all run fine on this motherboard/vrm with PROPER cooling (Vrm and behind socket + my scythe mugen4) ran fine. Your overclocking headroom on that board is probably very little though. I know these run at stock on these boards with proper cooling but have only ever overclocked on 970 extreme4/970a/g3.1/990extreme.

fx 8320 to 4.3ghz on air with a 4+1 phase so it CAN be done on asrock 970 extreme4 (same vrm as the 970m pro3) but the vrm needs a 50-70mm fan over it same with behind the socket. Also the asrock load-line calibration settings are a bit screwed up so you will have to adjust those to get temps and voltages stable. It really depends onw hat you want to do with your parts.

Considering the voltage of the fx-8370e I think you could run it with the noctua fan and a VRM spot fan at stock setting especially if you turn off turbo/apm and lower the voltage if you have a good chip. As for switching from phenom II to fx-series I cannot say,... and is it worth the price drop of 120eu? I dont think so if you want any foreseeable upgrade future or a performance gain... Hopefully someone else can answer too. I managed to get a bunch of fx-series processors for free so getting some cheap asrock boards was a bargain.
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Sep 28, 2015
Thank you for the comments! I've been looking at various benchmarks, considering the possible gains, the cost and the trouble I'd have to go through just to switch the CPU, and while it would still be interesting to try the FX-8370E just for the heck of it, it just doesn't seem worth it for what I'd have to pay for the CPU. I could get a Ryzen 5 1400 for almost the same cost. Of course I'd also have to invest in a new motherboard, new RAM modules etc., but I could then reuse some of my current parts and then gradually renew the rest so that I'll end up with a Phenom II and a Ryzen build. Or then I'll just play the waiting game and get it all in one go, which would save me the trouble of taking my current build apart. In any case, the FX-8370E-fever has gone down for the time being.