The data sheets for the Durabook R11 and the Durabook S15 list the Core i5-1235U and, as an option, the Core i7-1255U. The Fieldbook P122G2 comes only with the i7-1255U according to its data sheet. Both processors belong to the 12th generation of the Intel Core line, and on Intel's pages they sit close together: both have 10 cores, 12 threads and 12 MB of cache. The difference lies in a few numbers. This article puts them side by side, shows which devices from our data sheets list these processors, and says for which tasks the higher tier pays off. The processor values come from the specification pages on intel.com (ARK), retrieved on 20.10.2026. Type designations and entries change, so check the current status before you order. We do not quote prices. For the vPro question that comes with both types, see the article Intel vPro in rugged laptops and tablets: remote management and security.
Intel gives the first quarter of 2022 as the launch period for the Core i5-1235U and the Core i7-1255U, and Intel 7 as the process. Both have 2 performance cores and 8 efficient cores, 10 cores and 12 threads in total. Both have 12 MB of Intel Smart Cache.
The power envelope and the interfaces do not differ either. Intel lists 15 W base power and 55 W maximum turbo power for both. For memory, Intel gives up to 64 GB with 2 memory channels. DDR5 up to 4800 MT/s, DDR4 up to 3200 MT/s, LPDDR5 up to 5200 MT/s and LPDDR4x up to 4267 MT/s are supported. Add up to 20 PCIe lanes (PCIe Gen 4 at the processor), Thunderbolt 4 and up to 4 displays: up to 4096 x 2304 at 60 Hz over HDMI and up to 7680 x 4320 at 60 Hz over DisplayPort. The maximum operating temperature of the chip (Tjunction) is 100 °C for both, and Intel lists both under “Intel vPro Essentials”.
Moving from the i5 to the i7 therefore brings no additional cores, no more cache, no more memory and no different vPro tier. Thunderbolt 4 is also available with both: according to their data sheets, the Durabook R11 and the Durabook S15 each have one such port. What it does in daily use is covered in the article Thunderbolt 4 on a Rugged Notebook: Benefits and Limits.
Intel's pages differ in four values:
| Feature | Core i5-1235U | Core i7-1255U |
|---|---|---|
| Maximum turbo frequency of the performance cores | 4.4 GHz | 4.7 GHz |
| Maximum turbo frequency of the efficient cores | 3.3 GHz | 3.5 GHz |
| Graphics units (execution units) | 80 | 96 |
| Maximum dynamic graphics frequency | 1.20 GHz | 1.25 GHz |
By calculation, the peak clock speed of the performance cores is about 7 % higher on the i7-1255U than on the i5-1235U, and about 6 % higher on the efficient cores. It also has 16 more graphics units, a fifth more. These are upper limits, not sustained values. The pages we retrieved list neither a base clock for the cores nor a benchmark result. We therefore give no percentage for performance in applications; the calculation covers only the upper limits of the clock speed.
Intel writes “Intel Iris Xe Graphics eligible” for both processors and states no condition for it on the pages we retrieved. Our data sheets say nothing about the integrated graphics. If graphics performance matters for your application, we clarify that before the quote.
According to Intel, the two processors have the same power envelope: 15 W base power and 55 W maximum turbo power. For the i7-1255U, Intel also lists 12 W as minimum assured power; the page for the i5-1235U has no such entry. The higher clock speed of the i7 therefore comes out of the same power envelope. How long a device holds a high clock speed depends on the housing and the cooling. Intel gives no sustained values for this, and our data sheets state neither a sustained power nor a fan. Our assessment, not a statement by Intel: in a closed housing at a high ambient temperature, the gap between the tiers can be smaller in continuous operation than the turbo values suggest.
Do not mix up two temperature figures. The 100 °C from Intel is the maximum operating temperature of the chip. The data sheets of the Durabook R11 and the Durabook S15 give -20 °C to 60 °C as the operating temperature of the device, and the data sheet of the Fieldbook P122G2 gives -20 °C to +60 °C. What the device figure means in the field is explained in the article Operating temperature: what −20 °C to 60 °C means in practice.
Battery runtime is also given only once per device in the data sheets, not per processor: 8.5 h for the Durabook R11 with 3950 mAh (optionally 6900 mAh with 15 h) and 12 h for the Durabook S15 with 7600 mAh. Whether the i7-1255U shortens the runtime compared with the i5-1235U is not stated in the data sheets. A higher clock speed raises power draw during load peaks; how much that affects a shift depends on the load profile. If you need a full shift without a charging break, plan around the battery option or the swappable battery instead, see Swappable Battery and Hot-Swap: Continuous Operation Without Shutdown.
Five of our data sheets list one of the two processors. We show three of them in the table; it comes from the core data tables of the data sheets.
| Device | Display | Processor per data sheet | Memory | Battery | Weight |
|---|---|---|---|---|---|
| Durabook R11 | 11.6 inches | Core i5-1235U with vPro; optional Core i7-1255U with vPro | 8 GB (DDR5, 4800 MHz, 1 slot), optionally up to 32 GB | 3950 mAh, 8.5 h; optional 6900 mAh, 15 h | 1.2 kg |
| Durabook S15 | 15.6 inches | Core i5-1235U with vPro (standard); optional Core i7-1255U with vPro | 8 GB to 64 GB (DDR5, 4800 MHz, 2 slots) | 7600 mAh, 12 h | 2.6 kg |
| Fieldbook P122G2 | 12.2 inches | Core i7-1255U | 16 GB | 6300 mAh, tool-free swappable | 1600 g |
On the Durabook devices, the device sets the memory limit, not the processor: Intel gives 64 GB for both types, while the Durabook R11 goes up to 32 GB according to its data sheet and the Durabook S15 up to 64 GB. The data sheets of both devices list the processors “with vPro”; Intel places both in the Essentials tier, and the consequences are in the vPro article. The data sheet of the Fieldbook P122G2 names only the i7-1255U, so there is no choice between the tiers. If you need more graphics performance on the Durabook S15, check the separate NVIDIA RTX A500 graphics card, which the data sheet lists among the integrated options, instead of the processor tier. The laptop comparison table and the tablet comparison table show further features of these devices.
Two further data sheets list the processors but are not in the table.For the Getac UX10-EX, the data sheet has described the 5th generation with Intel Core Ultra since 20 October 2026; the 12th-generation Core i processors belong to the superseded previous generation.
Compared with the i5-1235U, the i7-1255U brings a higher peak clock speed and more graphics units, and Intel lists nothing beyond that. A worked example: if a task that depends only on clock speed takes 10 seconds on the i5-1235U, the roughly 7 % higher clock speed of the i7-1255U saves less than one second. On short tasks that is barely noticeable. On long, steady loads it adds up, as long as the device holds the clock speed.
In our assessment, the higher tier pays off in these cases:
Then there is headroom. If a device stays in service for several years and the software becomes more demanding in that time, a clock speed 7 % higher is a small reserve, but it is one. In our assessment the higher tier is not justified when the device mainly runs forms, web applications, data capture or ticket systems.
If you are weighing the processor tier against the configuration, include these options from the data sheets:
Two related processors carry the Enterprise tier at Intel. In all the values compared here, the Core i5-1245U has the same figures as the i5-1235U: 10 cores, 12 threads, 12 MB of cache, up to 4.4 GHz on the performance cores, up to 3.3 GHz on the efficient cores, 80 graphics units, 1.20 GHz graphics frequency, 15 W and 55 W. The Core i7-1265U reaches 4.8 GHz and 3.6 GHz, has 96 graphics units at 1.25 GHz and otherwise matches the i7-1255U.
Between the i5-1235U and the i5-1245U, the difference in these values is therefore only the vPro tier: Intel lists the i5-1245U under Enterprise and the i5-1235U under Essentials. If you need remote management without a running operating system, that is decided by the tier and not by the clock speed.
No. Intel lists 10 cores for both, of which 2 are performance cores and 8 are efficient cores, plus 12 threads. The i7-1255U clocks up to 4.7 GHz on the performance cores, the i5-1235U up to 4.4 GHz.
Not according to Intel: up to 64 GB is possible with both processors. The device sets the limit. The Durabook R11 goes up to 32 GB according to its data sheet, the Durabook S15 up to 64 GB.
No. Intel lists both processors as Intel vPro Essentials. According to Intel, remote management with Intel AMT exists only with vPro Enterprise, for example with the i5-1245U.
The data sheet names only the i7-1255U and no variant with another processor. Whether another processor variant is possible, we clarify with the manufacturer before the quote.
For forms, web applications and data capture, the i5-1235U is enough in our assessment. If you want a tablet with 11.6 inches, take the Durabook R11 with the i5-1235U. If you want the extra computing headroom, choose the i7-1255U there as an option and check memory and battery first. If you need a laptop with 15.6 inches, choose the Durabook S15, and if you need graphics, look first at the separate NVIDIA RTX A500 graphics card. The Fieldbook P122G2 with 12.2 inches and IP65 is the choice if you want the i7-1255U anyway; its data sheet lists 650 nits, the data sheet of the R11 lists 1000 nits as an option.
For these cases none of the three devices is the answer on its own: tasks with a lot of parallel computing load or 3D graphics, where only a test with your software shows whether 2 performance cores are enough, and uses that need remote management on a system that does not start, because both processors are vPro Essentials. Before the quote we clarify which processor is in the configuration and whether the Intel figures still match the status of this article.
The RobustBook team is glad to help you choose the processor tier.