Vcore and vdimm with A64

[andL64]

i recently killed my good ol' 3700+ because i setted 1,42V 41C in bios and changed tccd 2 oldschool bh-5 and set to 3,6V 250 DDR500 2-2-2 then safe cmos and also into the bios 260 3,8V 2-2-2 cmos save 3 secs booting then "pzzzt" cpu burned away still then i didnt use the 4V jumper anymoa but good to know it now!

thx tony (still 2 late)

seEn

[uOpt]

i recently killed my good ol' 3700+ because i setted 1,42V 41C in bios and changed tccd 2 oldschool bh-5 and set to 3,6V 250 DDR500 2-2-2 then safe cmos and also into the bios 260 3,8V 2-2-2 cmos save 3 secs booting then "pzzzt" cpu burned away still then i didnt use the 4V jumper anymoa but good to know it now!

So yours burned at 3.8 Vdimm and default Vcore. What was default Vcore on that 3700+. Probably 1.40 but might vary.

[andL64]

yes it was 1,4 bios but i set +104% so i got 1,42V in bios 41C and 3,8V vdimm => it burned...

[mursaat]

That reinforces the theory of vdimm/2 - 0.325v = min safe vcore.

3,8/2 = 1,9 - 1.4 + 104% = 0.444v -> Out of range

Sorry for your lose andL64 I see you've found a good replacement with that FX-57

[Warship]

that logics does not work.

Min-vCore with CnQ = 1.1v, max JEDEC specced vDimm = 2.85 gives a vRef of 1.425 which then gievs a max diff of 1.425 - 1.1 = 0.325v.

BUT

Would you really think AMD wouldn't have any kinds of safety-bounds?

I runt my vCore is 1.025 and my vDimm is 2.7v which would be a vRef of 1.35 which gives a diff of 0.325

[mursaat]

If you read through the thread, 0.325v is exactly the safety differential between vcore and 1/2 vdimm. And yes, without re-reading all the thread, IIRC someone arrived to that conclusion the same way as you, CnQ vcore versus JEDEC 2.85v gives you 0.325v.

With all this said, what do you meant with "that logics does not work"? You are clearly stating that it works with your 2 next statements

So AMD safety boundis that, 0.325v with max JEDEC specs

[Waffentraeger]

Sorry for posting this message here..
i have on cpu - +0.3v (mobo epox 9npa+u). but in real it is only +0.23-0.3v. Is it PSU problem, or problem in mobo power system??? thanks.

[uOpt]

Well Ladies and Gentleman,

it looks like, ironically, I am the first victim of this.

I got a bunch new BH-5 modules and tested various voltages, including 4.0. Although I am aware of the voltage issue discussed here and hence was careful to always have 1.55+ Vcore, my 3.0+ GHz CABNE is now fried.

It looks like I either forgot to set Vcore when setting Vdimm at some point after a CMOS reload, or maybe that the board applied Vdimm after Vcore during boot after fresh settings.

In any case, said CABNE now still kind of works but driving RAM fast doesn't work at all, and even with RAM at stock speed I get the most violent memory corruption I have ever seen. The filesystem on my clocking/testing installation was scrambled bejond imagination, even wiping out the boot code. This applies to all RAM, tried BH-5, TCCD and UCCC. The CPU's memory controller is fried. CPU still boots, though.

A re-test of the board with a different CPU and some of the same RAM is happy as normal.

[OCme]

I just got my new DFI nf4 Ultra-D board from new egg & it is revision (R.AD0), the one HW changes. Does anyone know if this Vdimm/Vcore issue was addressed with this revision, or is it possible to fry my CPU if not carefull... thanks!

[uOpt]

I just got my new DFI nf4 Ultra-D board from new egg & it is revision (R.AD0), the one HW changes. Does anyone know if this Vdimm/Vcore issue was addressed with this revision, or is it possible to fry my CPU if not carefull... thanks!

It is not possible to address this particular issue from a board level.

[OCme]

Thanks uOpt!

[uOpt]

Well Ladies and Gentleman,

it looks like, ironically, I am the first victim of this.

I got a bunch new BH-5 modules and tested various voltages, including 4.0. Although I am aware of the voltage issue discussed here and hence was careful to always have 1.55+ Vcore, my 3.0+ GHz CABNE is now fried.

Cancel that report, it was just bad PSU after all. And my CABNE works again after a few days of rest and rebuilding everything with my Powerstream.

I fact, it kicks very well
http://www.xtremesystems.org/forums/...&postcount=319

PSU RMAed...

[blazin-asian]

ok, so....

vdimm/2 - 0.325v = min safe vcore

vdimm = 2.65 (actually 2.6 but smart guardian sees it at 2.65)
vcore = 1.648 (1.475 + 113%)

this gives me.. 1v

am i safe running at these voltages? my UCCC chips run pretty low, but my CAB2E needs 1.6+ to run 3 GHz.

i didnt even know about the relationship between vdimm and vcore until now.

actually, one more thing. is it better to run

1. higher FSB with lower multi
2. lower FSB with higher multi

my mem can do 280MHz in case anyone was wondering. thanks

[neoman]

Well it depens on how your motherboard can handle high FSB .
300x9 and 270x10 there are no difference between performance.

[Alec]

Hey guys,
I am not sure if its teh RAM Ive killed, the mobo or the cpu...

Basically I have been running at 1.425vcore with 3vdimm for the past 3 months on my sandiego FX-55, been flawless in windows but in coutner strike it alwaysused to crash out every now and then with the error "the memory could not be "read"".

I installled a vapochill the other week, all running great but after about 5 days of having it on, I kept getting "SYSTEM_FATAL_EXCEPTION" BSOD of some of the kind - and then it would fail to boot up anymore (well it would get past windows loading screen then before login screen jsut BSOD for half a second and then reboot - it then got worse to just restart)...

It has stayed that way ever since pretty much, though if I move the RAM around into different sockets I can get my win2k hdd to boot up (I think i did it with a single stick of VX in dimm #1 on my dfi lanparty sli-d)

now I am just having ussues getting the damn thing to POST so I am letting it warm up (just had it at -32 hehe) and then I shall put back on the thermaltake big typhoon after taking out and reinserting the cpu.


I tried installing windows xp last night on my winxp hdd, and when it got to the detecting hard drives bit, it just BSODED with this message:

PAGE_FAULT_IN_NOPAGED_AREA

and technical info is:
*** STOP: 0x00000050 (0x00000001,0Xf74DA20,0x00000000)
*** ntfs.sys - Address F747DA20 base at F747B000, DataStamp 3d6de5c1


So really, I am not sure if its cold bug, RAM issues, messed up mem controller or mobo / bios issues.



The cpu hasnt had any decrease in performance overclockign wise for sure - still clocks 3GHz at 1.425vcore, though I think the vcore drips to 1.392vcore when fluctuation occurs....



Wonder if any of you could assist me?



Thanks so much in advance - I really could do with some help here, been off the pc for bout 5 days almost now and am really starting to feel ill from the stress of it all

Alec

[Alec]

UPDATE:
Just gont onto air cooling and put another stick of ram in, booted fine and now installind windows XP with not a single BSOD in sight!

Me hopes it was just either condensation or cold bug then.

[b1tterman]

well, nice then. my luck im not running those winbond voltage eaters

[sealion]

Yo guys anybody burned a cpu using high but reasonable cpu vcore with high vdimm?

[uOpt]

To my knowledge no death of a CPU has been directly attributed to this phaenomenon yet.

I always wanted to take the cheapest 939 CPU I can get and kill it just to verify the theory. At this time I don't have any Winbond memory left, however, so no go.

[Morgoth]

I ran stock vcore (1.37v) on my 146 on my ultra-d with 3.4v in the RAM with no issues.

none with any other vcore or vdimm (havent gone over 3.6v vdimm)

Hopefully new boards have fixed this problem if it existed (I just got my mobo)

Hopefully I will have 2gb of uccc coming my way eventually anyway

[FireD]

I have an Opteron 144@1,47v and BH-5@3,5v is this safe?

[mursaat]

Use the conservative formula to be safe:

vdimm/2 - vcore > 0.325v

Yours is 0.28v so you're OK

[HousERaT]

so if my math is correct (and my math sucks) my ram run at 3.5v needs to have at least 1.425v on the cpu core?