Resolved Running a non supported CPU on m/b

I recently tried to upgrade one of my PCs by installing a E 6850 (3.0 GHz 1333 fsb) on a Gigabyte motherboard (GA-945P-DS3 rev 2.0) which I thought supported it but it would not boot up probably because the CPU runs at a fsb of 1333 and the motherboard's top fsb is only 1066 (I thought that like memory a faster component would run ok at a slower speed)

I then tried a E7500 (2.93Ghz 1066 fsb) and it works ok (boots up and I have been running Flight Simulator ok).
I have noticed that the supported CPU list for this motherboard (GA-945P-DS3 rev 2.0) states that this CPU is NOT SUPPORTED (the rev 3.3 does support it but not the rev 2.0 which I have) yet my PC seems to be running quite happily. I contacted Gigabyte and they advised that I should only use CPU's listed in the supported CPU list.

Could someone please advise what MIGHT happen using a CPU which the manufacturer states is not supported? What is the worse thing that could happen and how likely is that to happen?

 

Fry the board or the processor or both. Maybe even the power supply, but I don't think that it would get the PS.

 

MrBill has answered your question regarding worst case scenario. However unsupported means just that, no support from the manufacturer, including probably voiding any warranty.

Windows XP <SP3 is unsupported, it doesn't mean it doesn't work

 

Thanks guys

Not sure if I pointed out that the fsb and speed of the unsupported CPU I am using (1066 2.93Ghz) is EXACTLY the SAME as another SUPPORTED CPU for this m/b eg

CPU fsb speed L2 cache supported?
Core™ 2 Extreme X6800 1066 2.93Ghz 4MB YES
Core™ 2 Duo E7500 1066 2.93Ghz 3MB NO

The only difference I see between the two is the L2 cache so why would one be supported and the other not?

Can anyone explain what the difference (other than the L2 cache) would result in one supported and the other4 not (just for my knowledge).

Thanks

 

Most likely because the motherboard was produced before the processor existed, hence no chance of testing therefore no support.

The above is my thoughts, I'm not stating this as fact as I've not done any research.

 

You have to remember CPUs are really dumb devices. They don't know how to do anything by themselves and have to be told (instructed - programmed) every step of the way, every time they are turned on. This is done by the chipset, of which the BIOS is a part of. As seen here, there are many chipsets for the current crop of Intel CPUs on the market today. And your chipset, the Intel 945P Express, as seen here (See Compatible Products > Processors in the Specifications box on the left panel) does not support the E7500.

What does that mean? Typically, it means the chipset does not know how to communicate with the CPU or utilize all it's features, and thus, will simply not function. But it may not use the same voltages so as noted, may result in a fried CPU.

 

Hi Bill
Thanks for the explanation but some of what I read at the links you included went over my head.
I can understand what you have 'said' HOWEVER
1) According to the Intel web page for the E7500, it runs at 0.85v - 1.36v. When I check my BIOS settings values it displays that the CPU voltage is 1.2875v which is well within the range given by Intel PLUS the CPU temperature even after running Flight Simulator X for an hour only gets to 38C-40C which is fairly cool. From that can I 'rest easy'? Should I adjust the voltage using GIgabyte's EASY TUNE motherboard utility to a slightly lower voltage?
2) According to Gigabyte's web page for the motherboard (GA-945P-DS3) the E7500 IS SUPPORTED for the rev 3.3 board (when the BIOS is reflashed to version F6i) but not for the rev 2.0 board (for any BIOS update) both of which have the the Intel 945P Express. You stated that the the Intel 945P Express chip does not support the E7500. Do you have any ideas why the rev 2.0 doesn't support it yet the rev 3.3 does? Note that I have the BIOS on my motherboard (rev 2.0) upgraded to version F6i.

 

Well, it would seem they reprogrammed the chipset to support the CPU. That happens a lot as new CPUs come out.

As far as the voltages, as long as the wrong voltage is not put on the wrong pin, I doubt there would be damage.

 

Bill,

The rev 3.3 m/b only supports the E7500 when the BIOS is reflashed to a later version. I am wondering why the rev 2.0 m/b doesn't support it with the same BIOS upgrade. Could there be something different with the actual m/b?
If it is the BIOS which 'controls' the CPU why then can the SAME BIOS (945P) upgraded to the same version be different on two revisions of the motherboard?
It seems very strange to me.

 

I agree with Arie. I can only guess. But I can tell you that motherboard makers do not control how Intel codes or controls their chipsets. New CPUs are released all the time. And motherboard makers may produce several revisions of the same model motherboard during the production lifespan of that board.

I was helping a guy with the same Gigabyte board I have in my machine. I insisted for dual-channel memory, he had to use slots 1 and 3 and my slots were color coded that way too. But he kept saying his required he use slots 1 and 2 and his board was color code for 1 and 2. It was becoming very frustrating for both of us until we figured out his motherboard, same model number, was Rev2.0 and mine was Rev 1.0. So there can be significant changes between revision numbers.

So you ask "why?" All I can say is, "because it happens. "

 

Yes I agree that answers should be made by Gigabyte.

I had initially contacted them but received what I considered 'standard answers' (eg read the manual) and considered those replies to be the easiest and quickest they could think of so that they could get onto the next persons question (they must get lots of help questions I guess).

I just could not understand why the same motherboard/chipset could vary in supported cpu's between one rev (version of the motherboard) and another with the same chipset especially for a cpu with the same fsb and speed as other listed cpu's, and so turned to the 'windowsbbs'. I am still wondering. Maybe it's what a previous reply stated 'that maybe Gigabyte had not tested certain CPU's and so listed them as N/A which could mean anything.

Thanks to all those who enlightened me.

 

I don't see why it should be that confusing. A motherboard incorporates all sorts of technologies from all sorts of suppliers who are making all sorts of advances all the time. Rev A may support USB 2.0 while Rev B may support USB 3.0. Rev C may support this new line of CPUs, and Rev D bigger RAM sticks.

Not everything is frontwards and backwards compatible, especially when the motherboard makers are coming out with entirely new models all the time too.

 

Bill

I am just learning (and have learned a lot since starting this post)

Ah but memory sticks are frontwards compatible are they not eg. you can use DDR800 memory in DDR667 slots (if the timings are the same). This is where it is not all clear to me. I would have thought that a slower speed CPU (of they same type/slot/fsb etc) should work ok in a motherboard designed for faster CPU's but obviously not.

 

You are mixing apples and oranges. Just because RAM "might" be compatible (and that is NOT a given), that IN NO WAY suggests CPUs are.

It's that "etc." that plays a key role here. There is MUCH more than type, slot, and FSB to compatibility. CPUs require "instruction sets" - that is, programming to run. Just because something "fits" in the same spot does not IN ANY WAY suggest it is a correct fit or that all the parties will be able to communicate. And if there is no communication, it will not work.

I think at this point if you still don't see it, you are just going to have to accept it. Because I have exhausted my explanations and cannot make it any clearer.

 

Point taken and I understand EVERYTHING I have read.
But I still cannot understand why two motherboards using the SAME CHIPSET (945P - which I understand is the "instruction set" only difference is the version of the m/b) can have different supported CPU's. There must be something else different between the two motherboards but what? North bridge and South bridge chipsets and BIOS version the same what else can there be?
I am bewildered.

 

Gigabyte's engineering team, back at the time that particular model was being developed and tested, should have an answer.