{"id":111201,"date":"2025-05-20T07:00:00","date_gmt":"2025-05-20T14:00:00","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=111201"},"modified":"2025-05-20T09:57:52","modified_gmt":"2025-05-20T16:57:52","slug":"20250520-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20250520-00\/?p=111201","title":{"rendered":"Why does Windows report my processor speed twice, with slightly different values?"},"content":{"rendered":"

If you open the Settings app and go to System, About, the first information block contains basic hardware information like the processor and RAM. But why does the processor speed get reported twice, sometimes with slightly different values?<\/p>\n\n\n\n
Processor<\/td>\nIntel(R) Core(TM) i7-4790 CPU @ 3.60GHz<\/span><\/td>\n3.71GHz<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

This field is actually showing two pieces of information, one after the other. Let’s break it down.<\/p>\n\n\n\n\n
Processor<\/td>\nIntel(R) Core(TM) i7-4790 CPU @ 3.60GHz<\/span><\/td>\n3.71GHz<\/span><\/td>\n<\/tr>\n
 <\/td>\nProcessor brand string<\/td>\nSpeed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The processor brand string comes from the unreliable<\/a> CPUID function codes 0x80000002 through 0x80000004<\/a>, which returns an arbitrary 47-character string\u00b9 intended to be used for processor branding identification.<\/p>\n

Some processor manufacturers include a CPU speed as part of that string,\u00b2 which is why you see the “@ 3.60GHz” appended to the CPU identifier.<\/p>\n

Windows itself does a rough calculation of the CPU speed and shows it after the processor brand string.<\/p>\n

My guess is that this system is being 3% overclocked since 3.71 is 3% larger than 3.60.<\/p>\n

\u00b9 Really 48 characters, but it is required to be null-terminated, so only 47 useful characters.<\/p>\n

\u00b2 Perhaps they do it to make it easier to detect overclocking or systems being marketed as faster than they really are.<\/p>\n","protected":false},"excerpt":{"rendered":"

One is calculated. The other is self-promotion.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[104],"class_list":["post-111201","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-tipssupport"],"acf":[],"blog_post_summary":"

One is calculated. The other is self-promotion.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/111201","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=111201"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/111201\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=111201"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=111201"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=111201"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}