My system's spiked as high as.... 56C according to MBM... Under load. I really have to fix that case's airflow problem... Asus A7N8X-E, AMD Sempron 2400+, Coolermaster PIPE101 with a SilentCat90 on it. But she's been as low as 42C under load in the winter (and downstairs where ambient temps are between 8C and 12C cooler). She's probably a little cooler now that I dropped that OCZ Modstream in 'er though...