Introduction

Intel have increased the top-end performance of desktop CPUs with their latest 8th Generation range. The main change has been the increase in cores for the i3, i5 and i7. At the top end the i7 now has 6 cores and 12 threads. With CPU prices the same as for the 7th Gen CPUs, this means you get a step up in performance per $.

Most of our customers need a fanless PC without compromising on performance or features, so the obvious question is "can I have a fanless PC with this new 8th Generation i7 ?"

The reason for this blog post is because the answer has been made more complicated by intel changing their approach to handling power in the i7 8700T, which is their lower-powered 35W TDP CPU, the obvious choice for a fanless PC. We have found that it cannot be used as a "like for like" replacement of the previous 7th Generation i7 7700T.

How we test

Using monitoring software like HWInfo64, it is easy to observe the instantaneous and average electrical power being used by the CPU, termed "Package Power". This is the power that the CPU is limiting when TDP values are enforced. We monitor this package power when running tests that use all cores at the maximum clock rate. Many of our customers will load a CPU in this way when rendering large videos or compiling large software packages.

Our approach has been to test using auto TDP settings supplied by motherboards. All our motherboards enable manual enforcement of TDP values, which will throttle performance to keep power levels at those specified. We do not supply our PCs with this type of throttling in place for these reasons: 

(i) as a customer you expect to get the performance you are paying for, not just in short bursts, but for extended work loads.  The i7 8700T will lower its clock speed to 32x (from 38x) after 30 seconds of all-core loading if you manually set the TDP to 35W. 

(ii) it is very easy to reset the motherboard settings, and any BIOS update in the future would do this. We would not want your PC overheating in the future because manual settings had not been re-applied to the motherboard BIOS.

Results

The i7 7700T will generally observe the 35W power limit, with some motherboards allowing software (like the torture testing Prime95) to increase power above 40W continually. The i7 7700T will also start to automatically throttle the CPU if its temperature approached 80°C.

In our testing we found that the standard behaviour for the i7 8700T is to have Package Power (TDP) of about 50W. And with Prime95, depending on the test, this can be over 100W. It will not throttle the CPU until the temperature approaches 100°C. If the CPU did reach near 100°C then the internal temperatures within the fanless PC would be far above what is safe for the motherboard, memory and SSDs.

Our fanless solutions that worked well with the i7 7700T, like the Ultimate Fanless or FC8-Series , cannot cool 50W continually for more than one hour, so we do not consider them suitable for the i7 8700T.

Conclusion

To enable customers to get the 40% increase in performance that the 8th Gen i7 8700T provides we have our new range of Sigao fanless PCs. This is an industrial grade solution that enables heavy duty use and can be relied on to provide excellent cooling for a high performance 8th Generation i7 PC.

If you only need performance at the level of the 7th Generation i7, then please consider our 8th Generation i5 PCs which have 6 core CPUs. We have them in a variety of different fanless cases and motherboards.