ZOTAC nForce 790i-Supreme overclocked dual-core processors not as successfully, but it demonstrated remarkable potential with quad-core CPUs. What if EVGA nForce 750i SLI FTW mainboard is also as good? Unfortunately, it isn’t. When we tried overclocking our Intel Core 2 Quad Q9300 the mainboard loaded the operating system only at 450MHz FSB, it couldn’t get even to 475MHz. So, looks like with quad-core processors the board is pretty average. Therefore, let’s take advantage of its excellent potential with dual-core CPUs overclocking.
If you remember, instability during overclocking on ASUS P5N-D mainboard (on the same NVIDIA nForce 750i SLI chipset) forced us to test its performance at very low speed of only 400MHz FSB. EVGA nForce 750i SLI FTW mainboard gives us an excellent opportunity to compare the performance of this platform against some Intel based board at 512.5MHz FSB and maximum overclocking of our Intel Core 2 Duo E8400 processor. Unfortunately, we couldn’t set Command Rate to 1T, but even 1025MHz with 5-5-5-15 timings is a pretty good result.
Everything went well at first, but then errors started popping up. Even in those tests that the board used to pass flawlessly before. Had anything changed? Yes, the temperature. The chipset North Bridge started overheating after sometime. Replacing the small default fan with an 80-mm one didn’t solve the problem. We had to lower the chipset voltage, but once it lowered from 1.5V to only 1.45V, the system could no longer work stably at such high FSB and memory frequencies. We can overclock the CPU to the same 4.1GHz by raising its multiplier to x9 and lowering the FSB frequency to 455MHz, but even in this case 1.45V of the NB voltage was not enough, and at 1.5V we got errors.
The chipset cooler on EVGA nForce 750i SLI FTW mainboard is efficient enough for nominal work mode, but during overclocking when the chipset voltage is increased, it can no longer cope. The heat distribution system is not designed right. The central heatsink gets scorching hot, while the additional heatsink remains just a little warm, because the heatpipe leading to it goes out of the middle of the central heatsink instead of its base. So, even though theoretically the mainboard can work just fine at 500MHz+ frequencies, in reality it turned out unable to cope even with 450MHz FSB. Maybe Nvidia nForce 750i SLI based mainboards are generally unstable during overclocking and high temperature is just another problem complicating things. Anyway, looks like we cannot rehabilitate EVGA nForce 750i SLI FTW, so all apologies are taken back.
Besides, we discovered one more problem that may make it difficult to overclock processors on EVGA nForce 750i SLI FTW mainboard. During our tests of ZOTAC nForce 790i-Supreme – a reference mainboard on Nvidia nForce 790i Ultra SLI – we saw that even a slight change in the FSB frequency from 1333MHz to 1350MHz was enough to disable Intel’s power-saving technologies. The mainboard increased the voltages in the BIOS on its own and then processor Vcore just doesn’t go down any more in idle mode. If we convert the quadrupled numbers into regular FSB frequency values, this overclocking will be by no more than 4MHz FSB.
EVGA nForce 750i SLI FTW did “better” than that. If you change the FSB from 1333MHz to 134MHz, i.e. only by 0.25MHz, the voltages in the BIOS go up and Vcore no longer lowers in idle mode. I really wish someone could explain to me why we deserve this!