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Underclocking CPU to work with SFF system

T

tokie

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Joined
Feb 20, 2009
Messages
46
Currently I have the following setup:
Intel 2500k (95watts)
ASRock Z77-E ITX
Radeon 6950
Sugo SG08 (15 liters)

I want to go even smaller than the Sugo SG08, probably to something like the Streacom FC7-EVO.

Of course I will have to go from my 6950 to a low profile Geforce 750Ti which I am fine with.

But I want to keep my CPU/Mobo/RAM if at all possible, since going to Haswell or something else will be a lot of money for new CPU+Mobo and really no significant performance upgrade.

Has anyone here underclocked the 2500k to reach a lower TDP? I am thinking of limiting the base clock to something like 2.4GHz and limiting the turbo to 3GHz. Would this fit the system in a 200watt PSU? I am worried the power load from 2500k (underlocked) + 750Ti would really be pushing this.

One other issue is that my 2500k has higher than average temperatures.

This machine will be running headless and streaming Steam games to my laptop. The 750Ti is necessary for hardware H264 encoding, and a decent CPU is needed for games. Main streaming target will be 1080p60.
 
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That's cool then :)

And the PSU? Is it a brick with a pico Adapter? Or something else?
 
I tried undervolting my son's i5-2500k but ran into problems when it went turbo. I didn't look into it any further. You could swap it with a low power cpu like an i5-2400S or pay a little extra for a 3570S. The S series is essentially the same except with a locked multiplier and starts of with a lower clock.
 
^^ Couldn't you just disable Turbo in BIOS? Might not be an ideal solution, if this is actually an issue for the OP, but probably better than buying a new CPU just for a case swap.
 
Could disable turbo but it negates one of the great benefits of SB/IB which is cool on idle and powerful when it needs to be. I would think he could get at least as much for a 2500K as a 2400S with only a few dollars more for a 3570S so it would not be a big expense.
 
I you have a "K" processor an the appropriate motherboard you can lower the turbo multipliers down below stock. When I had temporarily had a 4690k on a Pico PSU / Noctua NH-L9i heatsink with an HD 7750 I limited the max multiplier to 3.2 or 3.3 GHz to keep temps down.

The 750 Ti wattage and the 2500k underclocked will fit in a 200W window. My Pico PSU was rated to 160W and the system I had (4690k/HD 7750/2 SSDs) ran fine. Keep in mind the 95W is for the thermal envelope too.
 
phillyboy said:
Good catch. Would a single-slot low profile HD 7750 work for you?
Click to expand...

Unfortunately probably not. I would need an Nvidia GPU to properly use Steam In-home streaming.

I find QuickSync is not fast enough for 1080p60 encoding, and I hear NVENC is fast enough so that is why I would switch.

Perhaps I could look at a different case, but I really want to be under 8 liters and use a PicoPSU. All the Sugo cases except the SG08 I find ass-ugly so I would need to move away from Silverstone.
 
It will be a challenge to find a sub 8L case with dual slot GPU as most manufacturers have assumed a GPU requires a full PSU or at least an SFX PSU. Maybe the 750 will begin to change attitudes an new cases will emerge. You could always mod a single slot case that had a bit of extra "room" next to the slot.
 
Another thing you can try which I have not is limiting the power state in the bios. If I remember correctly on some boards you can set the max c state so effectively you can turn a k processor into a s or t by doing this. For example you could turn a 2100 into a 2100t (35w) by doing this as well.
 
tokie said:
Unfortunately probably not. I would need an Nvidia GPU to properly use Steam In-home streaming.

I find QuickSync is not fast enough for 1080p60 encoding, and I hear NVENC is fast enough so that is why I would switch.

Perhaps I could look at a different case, but I really want to be under 8 liters and use a PicoPSU. All the Sugo cases except the SG08 I find ass-ugly so I would need to move away from Silverstone.
Click to expand...

Look right in this forum at the Lone Industries L2, 5.3L and I have an i7 3770k with a Galaxy 750 Ti card running from a brick it's in the thread. Lone is about to do another run on these I believe.
 
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