I have a Hypersonic GX-7, which is basically a Sager 8790. What an amazing machine (when it works!)
I too am experiencing the flicker issue on all intensity levels. It has been in the shop a couple of times for this issue, too. Hypersonic's tech support is very good and they fix everything just fine, but it's 3 to 4 weeks each time it goes away for repair, which is a HUGE drag.
Here's the deal. Initially, I dropped it and the backlight in the display went out. OK, I admit, that was s dumb thing to do. But luckily I had purchased Hypersonic's accidental replacement policy, so I sent it in to them. Oddly, when they got it, the display worked and they could not get it to malfunction, even after several days of tests. They checked it out to make sure the fall hadn't damaged anything else, and sent it back to me. Everything seemed OK, except upon returning it to me, I noticed the screen started the flickering problem at it highest brightness level.
I called Hypersonic, and they sent me a postage-paid shipping label to send it back to them, and they fixed the flicker issue. Yaay for me. In the shop for 2 months, and I finally have everything back to working 100%.
Shortly thereafter, the motherboard went bad (which was probably due to the fall). Hypersonic sent me another postage paid label and I shipped it to them. They replaced the motherboard and a bunch of internals. 4 weeks later I get it back, and I am once again in love. This is July, 2005.
Everything is great for 6 months or so. Fast forward to November. Yesterday to be exact. My display starts its flickering problem again. The flicker is only intermittent, but it is annoying as hell. Sometimes it's fine for a few minutes, then the flicker comes and goes. Today I called Hypersonic, and asked them if they were aware of the massive reports of flickering issues on the Sager systems they're selling, and they claim to have no knowledge of any flickering issue. However, they do acknowledge that the flicker is NOT normal behavior, and I should return it to them for repair. I'm expecting another postage-paid shipping label from them tomorrow, although I may just send it myself next-day air, since UPS ground both directions really slows down the process.
To make a long story short, the Hypersonic / Sager laptops have beautiful - absolutely gorgeous displays when they're working properly. But, there is definitely some kind of flaw in the voltage output going to the screens causing this flicker which should be addressed by Sager engineering!
I have high praise for the Hypersonic repair team. That accidental damage / no dead pixels / extended warranty cost me an arm and a leg, but it has already paid for itself many times over.