AMD not adhering to 125W spec with FX8350?

[mmj_uk]

I found this interesting although not surprising given my experience with a Piledriver.

http://forums.anandtech.com/showpost.php?p=34588633&postcount=24

According to RD engineers from our HQ,

1. AMD has claimed that the FX-8350 to be 125W. However, during our internal testing, when the usage of CPU reaches 100% through Prime 95 for a while, the power consumption can exceed 125W and reaches 140W. With such condition on the 970A-G46, the high amount of power draw also causes the MOSFET to exceed its spec and will overheat.

Thus, to prevent such any potential hazard to the MOSFET, 970A-G46’s BIOS will trick the processor that its temperature is 225 degrees which will then allow the CPU to throttle. This is aimed to make the system stable in this condition.

2. We had tested using 3DMark and it did not cause throttling. Throttling only happens when the loading on a 125W CPU usage is heavy by the use of heavy burn-in tools such as Prime 95/OCCT, and such testing methods are not standard usage scenario or practical.

Please also keep in mind that this throttling behavior keeps system stable under such heavy-loading condition.

This is more of AMD’s issue on the FX-8350 because the TDP was rated lower than its actual value.

So AMD are shipping FX8350's with an actual TDP of up to (and possibly above) 140W and thus board manufacturers (on the cheaper boards at least) are having to implement throttling mechanisms to prevent crashes even at stock, this is because their VRM's are only rated at the official 125W spec as defined by AMD themselves.

Aside from being false advertising this is quite underhand by AMD.

 

[mmj_uk]

This is not really new, I am sure my 1090T at 4.1+GHz exceeded 125W in fact probably 140W. I expect an overclocked intel hexcore would also come close to that.

What TDP they run at overclocked is not AMD's responsibility, being honest about the TDP at stock speeds is.

What this boils down to is AMD are lying about the FX8350's TDP, presumably because if they were honest and called it a 140W chip then it would no longer be seen as an upgrade path for the majority of older 125W motherboards already out there which can't run it (at least not without throttling being added as a normal every day feature).

It affects many of the new boards too (though not the high end overclocking ones):

1> AMD set the official spec for FX8350 as 125W.
2> Motherboard vendors build boards for 125W CPU's as per the official spec AMD gave them.
3> AMD ship 140W FX8350's labelled as 125W.
4> Motherboard vendors find that their motherboards can't cope, add throttling to protect VRM's from damage & prevent crashing.

Pretty shoddy really.

 

[mmj_uk]

Prime95 is a real world application used to find Mersenne Prime numbers, also if you read the thread on Anandtech the guy witnessed the same throttling using Adobe Media Encoder.

In MSI's defence, they offered the guy a 'step up' to their top end board which supports 140W processors, they didn't need to do that given that the ones in wrong are AMD for ignoring their own spec. MSI's motherboard supports FX-8350 with a 125W TDP as per spec, it's not their fault if AMD are shipping FX-8350's with a higher TDP.

AFAIK all AMD (and Intel) processors previous the TDP referred to the maximum.

 

[mmj_uk]

AMD are not rating them at 125W power usage. MSI and the OP are wrong.

Really?
http://www.amd.com/us/products/desktop/processors/amdfx/pages/amdfx-model-number-comparison.aspx

Show me where FX8350 is listed as anything but 125W TDP.

This thead is about rubbish MSI mobos, not AMD's ratings.

In what way are they rubbish? they are value motherboards designed around the official spec. It's been mentioned on Anandtech that ASRock are echoing MSI's statement say but I can't find the source.

 

[mmj_uk]

This is what confuses me about this story. MSI are talking about power usage there, not TDP. It's not the same thing AFAIK...or is it?

The more power which is drawn the more heat needs to be dissipated, it's common sense really.

FX8350 is drawing more power than they should 'officially' and hence thermals/TDP are above what they should be, so vendors making value conscious motherboards are finding that there boards are not stable under load due to VRM's overheating/being overdriven and are implementing throttling mechanisms to protect them.

If this was a case of 'rubbish MSI' as you say then why is the FX8320 (also rated 125W TDP) apparently not affected?