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CPU clocked capped to 800 MHz

By vinod1633529964 ·
Tags: Hardware
My Dell OptiPlex 7050 is running too slow. The quad-sore i5 6500 2.5 GHz CPU clock is capped to 800 MHz max in BIOS. Disabling Intel SpeedStep did not help, nor did Factory Reset of BIOS. Any tips?
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That's the usual failsafe multiplier.

by rproffitt Moderator In reply to CPU clocked capped to 800 ...

There's a 100 MHz clock that is multiplied up and when the CPU is overheated or has other issues, the CPU protects itself by switching to the x8 multiplier.

"When a processor is stuck at the failsafe frequency there are 2 possible issues: bad heat dissipation or power issues.
Now since the CPU voltage is automatically lowered when failsafe occurs you cannot know which of the two issues are causing the failsafe."
- https://forums.tomshardware.com/threads/i5-6500-stuck-at-800mhz-and-8-multiplier.2608009/

-> I DO NOT EXPECT THIS TO BE A BIOS ISSUE GIVEN THE AGE. You didn't write this PC always did this.

It's old enough to have the CPU heatsink compound replaced and while we're in there, do the usual cleaning and fan check. The criteria for fans is "works like new."

1. Try the solution on page 2 of https://forums.tomshardware.com/threads/i5-6500-stuck-at-800mhz-and-8-multiplier.2608009/page-2?view=date
2. See https://forums.tomshardware.com/threads/4670k-stuck-at-800mhz.1749370/ for another area to try.

-> Again, at this age I would do the CPU heatsink work (it's a dollar's worth of compound), clean and fan check.

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CPU clocked capped to 800 MHz

by vinod1633529964 In reply to That's the usual failsafe ...

Turned out that the PC did not recognize the power supply, even though it is an original Dell power supply. The BIOS was capping the CPU frequency to 800 MHz. I replaced the power supply a newer one and PC is working fine now. Sharing my findings with a hope someone will add it to a checklist of things to try in such a situation.

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CPU clocked capped to 800 MHz

by vinod1633529964 In reply to CPU clocked capped to 800 ...

Since the old power adapter was also 65W, the problem was not its wattage but BIOS' inability to read its capacity. Is there any way to disable BIOS feature to check power capacity?

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Had to dig a little more.

by rproffitt Moderator In reply to CPU clocked capped to 800 ...

And yet I found no document on BIOS settings in regard to the external power supply but did find others that write using the next size Dell 90+ Watt adapter is known to cure this.

-> There are too many complaints about the 65 Watt adapter so I'm going to write the 65 Watt adapter is a bad idea.

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