I spoke with HTC yesterday regarding my wifi signal worsening.. 1 bar in same room as modem... He confirmed it was a known issue that would be resolved alongside the jelly bean ota before the end of September... Fingers crossed
That's bizarre, since I've just got mine back from repair after having a poor wi-fi signal. I contacted HTC via their support site, stated that I'd tried it on multiple routers, all with the latest firmware, my One X had the latest firmware, and I'd compared it with colleagues One X's (all later builds, I suspect) and they had stronger signal. I'd also compared it to other wireless devices that received excellent signal strength when I was listed as poor.
They replied with return instructions (no factory reset, no wait for OTA updates), and it was collected a few days later. In just over a week I had it back and wi-fi is now fine.
Try holding the phone facing towards you and pinching it just to the right of the camera (right hand thumb on screen, first finger against the raised part of the lens). If your wi-fi strength goes up it could potentially be a hardware issue. I also stated this in my mail to them.
I was getting low signal strength within feet of an access point and dropouts about 15 feet away. Seems OK now.
Sidenote: When it came back from HTC, the call volume was very low. Was just about to write back to them when I noticed a thread on XDA saying the speaker holes can get blocked, even if they don't look like it. People had reported solving the problem by running a squirt of canned air over the holes, pushing through them with a toothbrush or vacuum cleaning them. I can't vouch for how safe the procedure is, but making sure I'd poked every grill hole with a toothbrush bristle sorted it for me, even though it looked clean.