While browsing the profile of a strong player on youtube, I found a claim had been cited that a player with an IQ of 70 could be an International Master. Of course I don’t believe this. Does anybody believe it? When you match the memory and the planning skills of an IQ 70 player against the attributes of an IQ 125 player, I think the IQ 70 player must always be deficient and is never likely to succeed in competitions at that class level.
The claim seems not oly falso, but derogatory.
I don’t believe it’s likely, either. But I do believe that some skills most important in chess (pattern recognition, calculation) are not necessarily strongly correlated with a high IQ.
And what does IQ measure?
Saw some where today that in 1980s Garry Kasparov IQ was 135. Guess genius level is 140 so he did not quite make it.
A Harvard Medical School researcher did a journal article in around 1988 looking at the characteristics of grandmasters. The only interesting item I recall was that left-handedness was about twice as common among GMs compared to the general public.
I read somewhere that (IQ * 10) + 1000 gave the approximate ceiling for the rating one could achieve with the 10,000 hours of diligence. If Rusty’s post, above, is correct (noting Kasparov’s IQ as 135) that rule admits of some major exceptions. 
BTW, I’ve also read that chess skill is NOT tightly coupled to IQ.
Dunno about Grandmasters, but just average IQ is certainly enough to get one to 2300 rating.
I can’t say what it is that IQ measures. but apparently the raw score on an IQ test is converted differently according to the subject’s age. I wonder if they can correct for senior moments or brain fog.
I googled “gary kasparov iq”.The first link was to a sample test similar to the one that measured GM Kasparov’s IQ at 135. The 10 item sample test was extremely flawed in my opinion and many takers of the test felt the same way.
I saw a youtube video of Kasparov analyzing a win of his over Karpov and it was evident that a genius was speaking, overwhelming speed and accuracy of his thoughts are what impressed me the most. I doubt if the IQ test given did GM Kasparov justice.
In the middle of the 19th Century, Boden wrote, "“Chess skill is not necessarily associated with any other particular talent, nor with general capacity. It seems to be an exclusive faculty, a talent sui generis.” Looks like his judgment is more current than his gambit. 
I heard that Bobby Fischer had a 187 IQ. He had a good pedigree. His biological father was a PhD level mathematician who worked on the Manhattan Project. His mother was just short of being an MD.
I heard somewhere else that Judit Polgar has a 170 IQ.
Brady does not specifically cite a source for the IQ score, but that page references both Parade magazine and the journal Architecture.
On the main theme, I would not be surprised if there were some correlation between IQ test scores and chess progress. Many standardized IQ tests attempt to measure qualities that would seem applicable to chess. I also wouldn’t be surprised if there are outlying people with high reported IQs that are horrid at chess, and that there may be chess savants with average or low IQ.
However, I would think that were you to drop me Survivorman-style with a chess set I’d rather spend my time playing a 100 rated opponent who has been an outdoorsman all his life (after we establish the basics) than a Grandmaster whose closest contact with nature has been television.
The Johnson-O’Connor Foundation (offices in major U.S. cities) measures factors and results which purport to show aptitudes for various careers. One of their tests is called Memort for Design. Possibly such a test would correlate with chess ability.
In a graduate school class in education, we explored various measures like IQ,EQ, personality tests, SAT, GRE, LSAT, and tests increasingly used by employers for job selection. Some conclusions drawn were that all were imperfect or even poor measures for projecting future success. Many of the tests were also culturally biased in how they were drawn up and evaluated. There were political and social ramifications in the use of the tests. Some studies indicated that attitude, individual drive, and ability to lose oneself in tasks were better indicators of performance. The problem with all of these measurements is the tendency to extrapolate too much from a singular source of information. It was a warning to us as educators not to put too much emphasis on only one measurement of performance but to use multiple measures to assess students skills and abilities. Unfortunately, high stakes tests, like ratings, are used to simplify a very complex process of learning and performance.