Undervolting amd phenom ii to deal with motherboards tdp limitations

[mohdasimsayeed]

I got a new system which unfortunately was carelessly assembled it has a motherboard which supports cpu of 95 watt max tdp but the cpu AMD phenom ii X4 955be which is a 125 watt tdp cpu ,( I used it for a couple of weeks before I learned that) since then the machine is powered off (me being overcautious).

I was thinking about underclocking and undervolting the cpu to 2.8Ghz and 1.20 VCore voltage. Will it help,will the board survive the processor then?

system configuration:-

CM elite 311 cabinet
CM GX450W psu
ASUS M5A78LM-LX motherboard
AMD Phenom II X4 955BE processor
Power color 6770 graphics card
500 GB seagate barracuda harddisc

 

[nna2]

are you sure it was running at full speed at all? i would check with CPU-z if it's even going 100%

 

[pauls3743]

New system, send it back. No system builder should build a system where the cpu draws more than the motherboard is capable of delivering.

 

[mohdasimsayeed]

I did not check it for 100% load, and I dont think I will ever got to 100% I am just a casual user.
and I cant send it back now its more than a month old I got it in working condition and it runs fine even now,

I was questioning about if i underclock and undervolt the cpu ,then the cpu will be drawing less power right, and that will mean lesser TDP
Will that mean the mother board will stay alright and what are potential problems and risks in doing so.

 

[DJDeCiBeL]

What nna2 is basically asking is does it ever actually run at 3.2Ghz (regardless of load, even)?

And I actually agree with pauls3743 here. The builder should never have done something like that in first place. He obviously didn't know what he was doing, and you should definitely send it back, somehow. It's not your fault. No point in trying to fix a problem that you didn't cause (and I'm pretty sure you can't "fix" by doing what you're suggesting, anyway).

 

[DJDeCiBeL]

I'm honestly quite surprised that it works at all, considering that NO 955 is supported on that board. http://www.asus.com/Motherboards/AMD_AM3Plus/M5A78LM_LX/#CPUS

 

[mohdasimsayeed]

yes it runs at 3.2Ghz sometimes,but mostly lesser than that because of cool n quiet setting,
and I've tried doing what pauls3743 suggests before I put up the question here.
If i go for this option that will mean buying a new motherboard and replacing it myself which I will consider as a last option.

I have got my underclocking and undervolting numbers from a website eXtreme power calculator which shows the wattage to be about 85 after doing so,

 

[DJDeCiBeL]

I have got my underclocking and undervolting numbers from a website eXtreme power calculator which shows the wattage to be about 85 after doing so,

In theory, that has a chance of working, but in practice, I don't think it will actually mean anything.

Regardless, you shouldn't have even had to worry about this, and you having to do that because someone else screwed up is just not right.

 

[mohdasimsayeed]

well the socket is AM3 (aint it) So whats the surprize and thanx for the link to asus website but actually i got alarmed when i saw that page ,If it havent been for that page I wouldnt be so worried at all

 

[DJDeCiBeL]

well the socket is AM3 (aint it) So whats the surprize and thanx for the link to asus website but actually i got alarmed when i saw that page ,If it havent been for that page I wouldnt be so worried at all

Because the BIOS shouldn't even recognize it to be able to boot. Somehow, it IS recognized (or at least enough that it works), but I don't know how or why.

 

[mohdasimsayeed]

Well I agree with you. You are 100% right bios wont recognize it,

And I know its not right but i just cant argue with the system builder,
guess ill have to buy a new mother board then?

or should i try running it and replacing the mother board when it burns out,will there be a damage to the processor also

 

[DJDeCiBeL]

or should i try running it and replacing the mother board when it burns out,will there be a damage to the processor also

Since it seems to working correctly (somehow), I suppose it's ok, but I honestly don't know how using a higher TDP CPU than the board can support will affect it over time. It may be fine forever, or it may fry tomorrow. I really don't know.

The safest bet is to get a new board, yes, but man, I hate that that's the best option in all of this.

 

[mohdasimsayeed]

And I forgot to mention look take a look at this page
http://www.gigabyte.com/support-downloads/cpu-support-popup.aspx?pid=3833

it has three deneb(955's) one 95 watt and two 125 watt. what does that mean
and the board supports my processor and is somewhat low cost will that be okey

 

[DJDeCiBeL]

And I forgot to mention look take a look at this page
http://www.gigabyte.com/support-downloads/cpu-support-popup.aspx?pid=3833

it has three deneb(955's) one 95 watt and two 125 watt. what does that mean
and the board supports my processor and is somewhat low cost will that be okey

It just means that it will support all the 955's (unlike that Asus board, which as we know, doesn't support any at all).

But yes, that board will be fine.

 

[nna2]

there appears to be 2 revisions of that board, 1 that supports 95W (rev 4/5) and one that supports 140 (rev 3.1)... so keep a close eye on that if you plan to purchase it

 

[mohdasimsayeed]

Thanx for that info

 

[mohdasimsayeed]

Since I would be replacing the mobo,I was thinking should i try the thing I asked earlier underclock and undervolt the cpu,

What will be the best way to know if the thing worked,are there any risks other than destroying the mother board(which either way has to be replaced)

 

[nna2]

i suggest getting CPU-Z, if i wouldn't be suprized if it's running at 800MHz

 

[mohdasimsayeed]

yes its is running at 800Mhz
but it changes to higher values ones in a while then comes back to 800Mhz

The multiplier changes from 4 to 16 every time a new program opens and then settles down to 800Mhz with multiplier 4

why wouldn't you be surprized about what

 

[nna2]

well that CNQ, but is it running fine under load?

 

[mohdasimsayeed]

I havent put it under full load since i learned the build was with unsupported cpu
well it has been up for 4 hrs now temperature is 45c and Mother board temp is 42,
everthing appears fine,

but before i knew that the build was wrong i spent countless time on COD mordern warfare 3

 

[mohdasimsayeed]

Well could it be that its one of those 955 with 95watt TDP and cpu z is showing 125 watt just because it is not for my board ,

would that explain why it appears fine to me,
(well I went to the builder before i posted here and he ran the system for half an hour or so playing COD and it checked out fine thats why he refused to take back the system)

 

[nna2]

cod isn't a very good benchmark, they haven't updated the engine since the 3rd which was released in 2006, so it's not really a system destroyer... somthing like prime95 for half an hour would show problems, err linX as well, i get more heat output from that one

 

[mohdasimsayeed]

Okey I'll try prime95
So what is the max safe temperature for CPU and Mobo

 

[nna2]

61C is about tops for phenoms