Alienware 17 (R1) CPU not detected

[Khron]

Ok, i swear, i'm running out of ideas

So, i've had this Alienware 17 R1 (Haswell) brought to me. Allegedly, the owner tried to undervolt the cpu(?) because he was having overheating issues. Odd / unlikely, but fair enough.

Initial status - laptop turns on (ie. the lights & hdd's & stuff), but that's about it. No POST, no backlight, no beeps, nothing at all, with or without RAM.

Step taken: fresh BIOS chip, programmed with a dump found online (de-whitelisted).

Result: Still no backlight, but "at least" now i get series of 7 (seven) beeps, which in Dell / Alienware language, means the CPU doesn't get detected.

Since the cpu had supposedly been messed with, i figured i'd try to eliminate that variable. Stock it had an i7-4940MX; i found an i3-4000M for not too much money, to use as a test-cpu. No dice, same 7-beep stuff.

I've yet to probe ALL the voltage rails, but the ones i could reach on the top of the board, all check out - 5v / 3.3v main rails, the 1.35v and 0.675v for the RAM, 1.05v, 1.5v. At least, at the point of generation, anyway.

I'm getting 1.7v on the VCC_CORE rail, which is a bit on the high side, and from that Th3_un1qu3 tells me, that happens when the cpu isn't detected (properly).

I'm attaching the schematics / service manual for this board.

So... What the hell's the "cpu detection protocol" in computers?

Now that i think about it, i'm almost starting to doubt the "validity" of that bios dump i found. But then again, complaining about the cpu is still more than it did when it first came in...

Any ideas, anyone?

[dellxps15]

Re: Alienware 17 (R1) CPU not detected

hi check voltage on: pq502 pin 5-6-7-8 , pl501
pq506 pin 5-6-7-8 , pl502
pq510 pin 5-6-7-8 , pl503

then check carefully pu500 voltages. pin 17 , 8 , 3 , 5 , 16 , 22, 23 for now.

also pu501 voltages on pins,

edit: before check all those voltages, check pu501 voltage first and report back

[Khron]

Re: Alienware 17 (R1) CPU not detected

Umm... If you'll read a bit more carefully, i *DO* have Vcc_core present, but it's a bit high.
Also, i should add that even without the fan connected, the cpu heatpipe gets warm. Not hot, i can keep my hand on it all day long, but you can tell it's on.

But fine, just so you won't say i'm not cooperating:

CPU_B+ = 15,7v (i'm running it off the battery), that goes to the drains of all those three FETs

On to PU501.
17 - 15,6v (it's the B+)
8 - 1,7v (FB)
3 - 3,3v (Pgood)
5 - 0v (VR_hot#)
16 - 5,1v (5Valw)
22 - 0,6v (PWM3)
23 - 5,1v (5Valw)

Hmm... That pin22 voltage is a bit low, considering it's supposed to be connected pretty much directly to the 5v rail via PR523.
Edit: Nevermind, i mis-counted - that 0,6v was on pin 21, in fact...

[dellxps15]

Re: Alienware 17 (R1) CPU not detected

Umm... If you'll read a bit more carefully, i *DO* have Vcc_core present, but it's a bit high.
Also, i should add that even without the fan connected, the cpu heatpipe gets warm. Not hot, i can keep my hand on it all day long, but you can tell it's on.

But fine, just so you won't say i'm not cooperating:

CPU_B+ = 15,7v (i'm running it off the battery), that goes to the drains of all those three FETs

On to PU501.
17 - 15,6v (it's the B+)
8 - 1,7v (FB)
3 - 3,3v (Pgood)
5 - 0v (VR_hot#)
16 - 5,1v (5Valw)
22 - 0,6v (PWM3)
23 - 5,1v (5Valw)

Hmm... That pin22 voltage is a bit low, considering it's supposed to be connected pretty much directly to the 5v rail via PR523.

u must read before my edits: first report voltage on pu501; u are reporting voltage on pu500

pr523 must be 0 omh. remove power to board and check its value.

[Khron]

Re: Alienware 17 (R1) CPU not detected

Oops, typo - yes, that was PU500

See the edit in my previous post.
In fact, PR523 shouldn't be there at all - that's what the @ symbol means, next to it. And if that PWM signal was tied to 5v, PU501 wouldn't be doing anything

NOW let's see PU501.

[Khron]

Re: Alienware 17 (R1) CPU not detected

PU501:

Pin 1 = 2.1v
Pin 2 = 6.2v
Pin 3 = 0.6v
Pin 5 = 4.4v
Pin 6 = 5.1v
Pin 7 = 5.1v
Pin 8 = 1.7v

Scope traces look pretty normal too - high duty-cycle on the low-side gate, low duty-cycle on the high-side gate, PWM's there.

Somehow, i kinda doubt this is a Vcore issue...

[dellxps15]

Re: Alienware 17 (R1) CPU not detected

qc3 voltage ? page 11 on schematic

[Khron]

Re: Alienware 17 (R1) CPU not detected

There are two rows of caps "inside" the window of the metal backplate, under the cpu. On one side it's the Vcc_core decoupling caps, and on the other side there are four 0805 caps, decoupling the VDDQ - i DO have 1.35v on those.

Like i said in my first post - at least from a power point of view, i have all the main rails, as far as i can tell.

[Djosla]

Re: Alienware 17 (R1) CPU not detected

I can assure you that 7 beeps on dell never had anything to do with cpu...it was always gpu/nb problem although it states cpu problem on dell site...

[Khron]

Re: Alienware 17 (R1) CPU not detected

Well, that's kinda-sorta what i figured, since it kept doing the 7-beep thing even with a known-good cpu.

[Khron]

Re: Alienware 17 (R1) CPU not detected

I don't suppose anyone happens to have a BIOS dump from a working Alienware 17 (mid-2013), hmm?

[Khron]

Re: Alienware 17 (R1) CPU not detected

On a separate note, there's a chance i might not have an "H_CPUPWRGD" signal. At least i'm reading 0v if i probe right on the empty pad in the XDP header (page 7, top right). There's one tiny trace snaking away from that pad, going to an unpopulated component, but i'm reading 0v on all the pads around that (it's a set of 4).

PCH_PWROK, IMVP_PWRGD and SYS_PWROK are all present (3.3v, page 18, bottom left).

[atsio]

Re: Alienware 17 (R1) CPU not detected

Have you tried it without the mxm?

[Khron]

Re: Alienware 17 (R1) CPU not detected

With it and without it, same story.

Still hoping / waiting for a "good" bios dump, or some interesting idea. I've "even" reflowed the PCH a couple times, with no change (for the better or for the worse).

[atsio]

Re: Alienware 17 (R1) CPU not detected

Extract original bios, upload it, give your laptop exact model number and service tag to be able to help you.

[Khron]

Re: Alienware 17 (R1) CPU not detected

Extract it... from where, exactly?

I'm attaching a zip of the latest BIOS from Dell's site, that i downloaded a few days ago. Right now, for some mysterious reason, that page says "The product you've selected does not have or require updates."

Either way, the service tag is 4B6GH12, and the model number is "Alienware 17" ("R1", mid-2013, NOT M17x), came stock with i7-4710MQ and a GTX880M.

[atsio]

Re: Alienware 17 (R1) CPU not detected

we need and the original from uh14

[Khron]

Re: Alienware 17 (R1) CPU not detected

Umm... Excuse me, what?

[atsio]

Re: Alienware 17 (R1) CPU not detected

Read with programmer original bios from UH14 and upload it

[Khron]

Re: Alienware 17 (R1) CPU not detected

I just finally got around to doing that. My programmer took about 10mins (635sec) to read the whole 8Mbyte (64Mbit) chip, and it turns out it's EMPTY (checksum 0x0, content's full of FF's).

I most definitely have NOT erased it, although it being empty might very well explain why the laptop didn't do or say anything, when it first came in.

Like i said in my first post, only after i replaced the bios chip (with that dump that i had found), did it start the 7-beep thing.