Swapped i5-750 for i7-870 and no POST

wader

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May 8, 2014
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Hi Folks,
My Asus P7P55D motherboard worked well with:

i5-750 processor
8GB Corsair DDR3 RAM at 1333MHz
Asus GTX-260 graphics card

and a recent bargain led me to try swapping the i5 for an i7-870 processor that came out of a working business machine. The "new" CPU was clean and I cleaned up the Intel CPU cooler, then installed that i7 and used a bit of Antec Formula 7 thermal paste when reinstalling the cooler.

I also installed a GTX-760-based graphics card as another upgrade.

When I plugged in the AC cord, the Standby Power LED turned on (which is correct behavior) and pushing in the Power button on the case turned on all fans (i.e., CPU, graphics card, case, power supply) as one would expect. However, there is no POST beep or display output as power-up starts - actually, the whole system seems to power up fans and drives for about 1 second, turns everything off for about 3-4 seconds, then repeats that cycle until the AC cord is unplugged - i.e., the case Power and Reset buttons are ignored by this point.

I never set the CPU or memory to run overclocked/higher voltage, so was hoping that vanilla configuration would allow a simple processor change. I have downgraded back to the old graphics card and that has made no difference in these symptoms, which leads me to believe they are somehow related to the "new" i7 processor in this configuration. Or, maybe the processor I was sold is actually bad.

Thinking of going back to test with the old i5 processor again as a test, but before doing so was wondering if this situation rang any bells for advice, please.

Thanks.
 

wader

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May 8, 2014
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I agree, that seems the next logical step. Was hoping this might be a recognizable issue and possibly avoid downgrading to test, but will do so and report back.

Thanks,

- wader
 

wader

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May 8, 2014
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I tried using the CMOS reset jumper while the i7 was installed, but then the system wouldn't even attempt to power up. Assuming going back to the i5 works, perhaps I can do a reset then and immediately shut down, reinstall the new i7 and try that out . . . ?
 

wader

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May 8, 2014
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Well, darn. I just went back to the i5 processor and the same symptom came up. Coincidentally, another web search brought up a topic with the same symptoms and similar conditions, where the issue turned out to have been a bent pin which required a new mobo:

http://forums.anandtech.com/showthread.php?t=2127347

Not sure how I will be able to diagnose a potential bent pin in this case, but it may be that a new mobo is unexpectedly now on my list. I'm usually extremely careful with h/w changes, too. Ah, well.

techgeek: Yes, I was running latest BIOS level with this board.

Thanks very much for the advice thus far, folks. Will followup with any findings/resolution, of course.
 

wader

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May 8, 2014
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Just pulled one out of the drawer, but the only way I can see this working is to remove the motherboard from the case. This will take awhile, will get back to this after work tomorrow.

Thanks for that link, gives me something constructive to work with.

- wader

 

wader

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May 8, 2014
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I've also done those things, thanks - notably, I didn't see any pins that could be bent on the processor chips. They appeared relatively flat, essentially laying on top of the pins within the socket and then pressed together by the clip.

There was some thermal paste residue covering one of the contacts on the i7 chip (not from me), which has since been cleared away.

My first pass viewing the socket didn't show obvious bent pins, though. Still exploring.

- wader
 

wader

Honorable
May 8, 2014
13
0
10,510
Hi Folks,
I'm afraid there is not a satisfactory answer to my original post, at least in terms of fixing things with the h/w originally on hand. Various tests with the motherboard taken out and no-or-some peripherals attached led to the same, non-POSTing results with either the new i7 processor or the old i5 processor. I tried all combinations of memory sticks, jumpers, etc. There were no obvious bent pins in the processor socket area, either.

In the end, I purchased a new LGA 1150-based ASUS board+processor+power supply and am using the same memory, peripherals + case - after going through some online research, I have Windows 7 64-bit running with UEFI.


Thanks for your consideration, sorry that I couldn't offer a more substantive reply.