Foxconn LGA1156 sockets may hamper extreme overclocking


— 2:52 PM on October 15, 2009

Think twice before busting out that tank of liquid nitrogen and overclocking the pants off a Lynnfield PC. Or, at least check the brand name at the back of the socket retention mechanism. An article posted on AnandTech this morning suggests LGA1156 sockets manufactured by Foxconn may not make sufficient contact with pads on the underside of the CPU, which could cause nasty burns on the socket and processor at very high overclocks.

The first reports of the burnouts appeared on the XtremeSystems Forums last month. Users posted photos of melted sockets and burned contacts on Core i7-800 processors, eventually laying blame on the sockets. Intel's Francois Piednoel responded in the thread, attributing the problem to slight oxidation and overzealous overclocking:

Think about it ... at 1.65V, you are around 250watts ... this is 150AMPS!
gigabyte gave what the Overclockers asked ... now, use it with moderation ... I tested on a mecanical [sic] thermal dummy ... the [Gigabyte GA-P55-UD6] can deliver up to 160AMPS without occilation [sic] ... at this point, you are more than 2x the specs for currents ... and 60% over the voltage ...
and 263% of the based power ...

Piednoel added:

my guess in those cases is "finger print" or oxidation due to [liquid nitrogen] condensation plus an incredible UD6 voltage supply that does not bend under load. (thing requested by the OC community)

Admittedly, the XtremeSystems forum thread starter only saw problems after pushing his Core i7-870 to a blistering 5.19GHz at a temperature of -102°C—you know, not exactly stock specs. The Core i7-870 has a base speed of 2.93GHz, and individual cores go up to 3.6GHz with Turbo Boost.

AnandTech's Rajinder Gill, who posted in the thread, sees a much more direct link to the sockets. He explains in his article, "We have damaged every motherboard in our possession for the P55 overclocking (extreme) shootout as well as two very expensive i7/870 processors." The article goes on to say, "Physical inspection and end-user reports all but confirm the issues only affects sockets manufactured by Foxconn at this time." (Foxconn makes sockets for a variety of motherboard makers, including Gigabyte and Asus.)

Gill also posted incriminating photos showing that some socket pins didn't leave marks on their corresponding CPU pads. He claims to have pushed Lynnfield CPUs further on boards with non-Foxconn sockets, too. Then again, he also points out that Lynnfield processors have fewer power-supply pins than their LGA1366 Bloomfield counterparts (175 vs. 250) despite drawing "similar levels of current" when overclocked. Perhaps LGA1156 sockets are simply less prone to extreme overclocks by design, then.

We've asked Asus and Gigabyte to comment and are still awaiting replies. In any case, though, Gill specifies that this problem "will probably occur only in extreme overclocking scenarios." We haven't suffered any hardware failures when overclocking Core i5 and i7-800 processors in our labs, and neither did Gill "with air or water cooling overclocking up to 4.3GHz." The vast majority of Lynnfield users can probably rest easy for now.

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